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Chromatographic analyses of the phloroglucinol derivatives in 213 collections of Dryopteris from eastern North America and particularly Quebec were made. The taxa studied were two diploid species, D. assimilis S. Walker and D. intermedia (Muhl.) A. Gray; two tetraploids, D. spinulosa Watt and D. campyloptera Clarkson; the triploid hybrid, D. × triploidea Wherry; all in the D. spinulosa complex. Also studied were the tetraploid species D. cristata (L.) Gray, the triploid hybrid, D. × boollii (Tuckerm.) Underwood, the tetraploid species, D. filix-mas (L.) Schott, and the diploid D. marginalis (L.) A. Gray. Both glandular and glabrous specimens of D. assimilis and D. campyloptera were studied, but it was found that these characteristics were not necessarily correlated with the presence or absence of phloroglucinols. Dryopteris campyloptera consists of plants which may be "phloroglucinol rich" or "phloroglucinol poor," while D. assimilis and D. spinulosa are both low in phloroglucinol content as compared to European plants. The geographical ranges of the species is briefly considered and the chemical uniformity of some taxa and the variability of others is discussed.

The development of the gametophyte of the fern Dryopteris thelypteris (L.) Gray was observed under sterile cultural conditions in order to recognize those features necessary for computer simulation of the thallus geometry. Drawings of plants at 12-hour intervals revealed that the triangular apical cell divides according to a left-right alternation of cell plate orientation and that cell lineages derived from vegetative daughters of apical cell divisions progressively enlarge and are pushed to the sides and down along the thallus. A computer program was written that includes both biological rules and laws of physical constraints. The computerized plant passed through the typical filamentous, juvenile asymmetric, heart-shaped and biauriculate stages. Descriptive morphology can become more objective by selection of simple traits as the criteria for an ontogenic reconstruction of an observed pattern.

Scanning electron micrographs of spores of Dryopteris filix-mas (L.) Schott, D. abbreviata (DC.) Newman, D. caucasica Fraser-Jenkins & Corley, D. arguta (Kaulf.) Watt, D. marginalis (L.) Gray, and D. fragrans (L.) Schott var. remotiuscula Komarov are presented. North American D. filix-mas is compared with the European species and the origin of this tetraploid is discussed using the available evidence from spore morphology, cytogenetics, and chromatography.

1. Under experimental conditions individual prothallia of Dryopteris mollis (Jaq.) Hieron., Matteuccia nodulosa (Michx.) Fernald, together with certain other polypodiaceous species, and Osmunda Claytoniana L. may be made to produce from two to many sporophytes. 2. If the prothallia are permitted to attain a size of 1-1.5 cm. in width across the wings before fecundation is effected, as high as five independent and self-nourishing sporophytes may be developed before the weakening or partial exhausing of the gametophytes. 3. If the sporophytes are carefully amputated as soon as they become plainly visible, a succession ofsporophytes can be produced on an individual prothallium. 4. If the massive prothallia develop proliferations as a result of the experimental cultivation, from ten to fifteen or more sporophytes may be produced.

Action of riboflavin, isoriboflavin and 2-thiouracil in the induction of 2-dimensional growth of fern prothallia.—The inhibition of cell division induced by 2-thiouracil in prothallia of Dryopteris filix-mas and Anemia phyllitidis is reversed by riboflavin as well as by its physiological inactive analogue isoriboflavin. This antagonism is not due to an in vivo interaction as stated by Yeoh and Raghavan, but is rather caused by an in vivo sensibilisation of photo destruction of the inhibitor during early phase of spore germination. Riboflavin as well as isoriboflavin strongly inhibit cell divisions in the prothallia of Anemia phyllitidis. In spite of a significantly reduced growth rate NO retardation of the onset of the 2-diniensional differentiation, as related lo a critical cell number, can be slated in the Anemia prothallia.

WALKER, S. (Liverpool U., England.) Cytogenetic studies in the Dryopteris spinulosa complex. I. Amer. Jour. Bot. 48(7): 607-614. Illus. 1961.-A comparison of the D. spinulosa complex, as represented in North America, is made with that in Europe. Although in North America, other Dryopteris species are known to hybridize with members of the complex, the report has been limited to species which compare directly with those in Europe. Three tetraploid species and 2 diploids, the latter representing at least 1 ancestral genome in the complex, are discussed together with the interspecific hybrids. Synthetic hybrids have been produced, involving taxa from both sides of the Atlantic. Evidence from these hybrids suggests that D. intermedia, of North America, and D. maderensis, of Madeira, are conspecific. CYTOGENETICAL investigation of the genus Dryopteris has revealed a reticulate pattern of evolution. The results of studies in the Dryopteris spinulosa complex in Europe were published in an earlier paper (Walker, 1955). Similar work on this complex, as represented in North America, has led to a much wider investigation involving many other associated Dryopteris species and hybrids (briefly reported, Walker, 1959). It has become impossible to present all the data obtained in a single paper and, to facilitate a direct comparison with the earlier work, the present report covers only those representative species and hybrids found in North America which are comparable with the members of the complex in Europe. The relationships between the various taxa on both sides of the Atlantic have been investigated by the synthesis of a number of hybrids between them. Details of the wider investigation into the genus Dryopteris in North America will be published separately. The D. spinulosa complex in Europe includes 3 allotetraploid species, D. cristata (L.) Gray, D. spinulosa (O. F. Muell.) Watt and D. dilatata (Hoffm.) Gray, which require 4 ancestral diploids to account for their origin. One of these ancestral diploids, the genome of which is common to both D. spinilosa and D. dilatata, is now represented by 2 distinct species (previously regarded as diploid forms of "D. dilatata"); one, D. assimilis S. Walker,2 is found in Britain and on the continent of Europe, the other, D. maderensis Alston,3 on the island of Madeira. These species are very different in their pinnation and spore size, but cytogenetic evidence indicates they are descendants from the same ancestral diploid (Walker, 1955). From crosses between D. assimilis and D. maderensis, 2 1 Received for publication January 24, 1961. 2 Dryopteris assimilis, sp. nov., S. Walker. Based on Lastrea dilatata var. alpina. Moore, Handbook Brit. Ferns, 3rd ed., 126 (1857). Dryopteris dilatata var. alpina Moore, Brit. Ferns, I, 225 (1859). 3 Dryopteris maderensis Alston, published erroneously as D. maderensis (Milde) Alston (Alston, 1956), but Milde used 'forma maderensis' as a descriptive phase, not as a taxonomic forma (Milde, 1867). plants were produced showing normal meiotic pairing but approx. 40% abortive spores which suggests gene imbalance (Walker, unpublished). More hybrids are necessary to establish this. Wild hybrids occur within the complex both at the tetraploid and triploid levels. Chromosome counts for some members of the complex in North America have been reported previously (Britton, 1953; Manton and Walker, 1953), and detailed spore studies have been carried out (Crane, 1953). More material has been sampled by me and additional counts made. This complex has caused confusion to taxonomists; hence R. C. Benedict, with a long-standing interest (1924) in the spinulose dryopterids, referred to them (1954) as "one of the most disputed of our native fern groups." Separation of the various taxa into distinct species or varieties still remains a problem to most authors; this is particularly exemplified in the new Britton and Brown Flora (Gleason, 1952) and Gray's Manual of Botany, 8th ed. (Fernald, 1950). The presentation of the latter was criticized by Wherry (1952). Nomenclature for the various taxa is at present under consideration. The use of the species epithet, C"austriaca,"' in place of "dilatata,." as in the Flora of the British Isles (Clapham, Tutin and Warburg, 1952), and in the new Britton and Brown Flora (Gleason, 1952) has already been criticized (Walker, 1955; cf. Morton, 1958). The name. D. spinulosa (0. F. Muell.) Watt, is also invalid but is retained in this paper since, so far, no satisfactory replacement has been published. Neither D. lanceolata-cristata (Hoffm.) Alston (Alston, 1957) nor D. carthusiana (Villars) H. P. Fuchs (Fuchs, 1958) appear to be satisfactory substitutes. The following is a list of the taxa discussed in this paper: D. cristata (L.) Gray; D. spinulosa (0. F. Muell.) Watt; D. campyloptera (Kunze) Clarkson; (syn. D. spinulosa var. americana [Fisch.] Fernald),; D. intermedia (Muhl.) Gray (syn. D. spinulosa var. intermedia [Muhl.] Underw.); "D. dilatata" (Hoffm.) Gray; D. X uliginosa (A.

Mass spectra of phloroglucinol derivatives recently isolated from African Dryopteris species are presented. Phloroglucides with n-valeryl side chain were found in these ferns for the first time. In the mass spectra they show strong peaks corresponding to loss of propene (C3H6) produced by McLafferty rearrangement, as shown in model compounds. Aside of the rottleron change (discussed formerly) this must be considered in order to avoid wrong interpretation, particularly when mass spectra are used to analyse mixtures of homologues, as usually present in the plants. If valeryl side chains are present other methods must be used therefore to measure the amount or show the absence of lower homologues with acetyl side chains.

The phloroglucinol composition in two tropical American ferns, Dryoperis parallelogramma and D. patula has been investigated. Dryopteris parallelogramma , a member of the D. filix-mas complex, contains filixic acids, which are a characteristic of the group. Dryopteris patula contains aspidin, as do its relatives in the D. dilatata complex, and albaspidin- AA .

1. Dryopteris rosea Walk.The full grown larvæ, in the beginning of July, feeding on Vibrunum acerifolium, the “Maple-leafed Arrow-wood,”* are, in their last stage, olivaceous brown, pale dorsally; dorsal line single, dark; a triangular dark patch on each side of the body commencing on segment 4 (I do not count the head) and bordered above the abdominal feet with pinkish; anal segment prolonged.

SUMMARYThe cytology of sixteen species of ferns indigenous to South India has been studied. The chromosome numbers in all these species are being recorded for the first time. The existence of more than one cytotype in South India has been observed in Cyclosorus interruptus (Willd.) Iko. Apogamy has been demonstrated in Dryopteris boryana (Willd.) C. Chr. and D. wallichiana (Sprengel) Hylander.An unusual meiotic behaviour leading to the production of 8 aberrant spores from a single spore mother cell was observed in a tetraploid Rumohra aristata. Abnormal meiotic behaviour was also observed in Tectaria sp. (T. paleocnemioides (v. A.v.R.) C. Chr.?) in which no spores were formed. The chromosomes following metaphase I group together to form an irregular mass which later degenerates.

The red pigments in ferns were identified for the first time as 3-desoxyanthocyanins. Apigeninidin and luteolinidin were found, mainly as the 5-glucosides but also in several other combined forms, in the juvenile fronds of eight species. They also occurred in the red sori of Dryopteris erythrosma. The earlier report of common anthocyanins in Dryopteris could not be confirmed, but pelargonidin and cyanidin derivatives were definitely identified in Davallia divaricata. The distribution of 3-desoxyanthocyanins in the Gesneriaceae, the family from which they were first isolated, was also studied. They were found in 18 of 21 species in the sub-family Gesnerioideae but were absent from 25 species in the sub-family Cyrtandroideae. These results support Burtt's recent re-classification of the two sub-families on the basis of presence or absence of anisocotyly and geographical distribution but do not fit Fritsch's division of the family based on the position of the ovary. A new 3-desoxyanthocyanidin, columnidin, was isolated from Columnea x banksii and provisionally identified as 5,7,8,3′,4′-pentahydroxyflavylium. While common anthocyanins (e.g. malvidin 5-glucoside-3-rutinoside and pelargonidin-3-rutinoside) also occur in the Gesneriaceae, flavonols are absent. The flavones apigenin, luteolin and diosmetin were identified in nine species. It is suggested that 3-desoxyanthocyanin production is basically a primitive plant character but that these pigments are synthesized in the highly advanced Gesneriaceae in response to natural selection for a bright orange-red flower colour.

Morphogenesis and differentiation of fern gametophytes (Dryopteris filix-mas) are strongly controlled by light. “Normal” morphogenesis, i. e. formation of two- or three dimensional prothallia, can occur only under short wave length visible light (= blue light). In darkness and under long wave length visible light (= red light) the gametophytes will grow as filaments. The blue light dependent photoreactive system which controls morphogenesis seems to be located in the outer layers of the cytoplasm. The control of morphogenesis is causally connected with the increase of protein synthesis under the influence of blue light. In the present paper the influence of red and blue light on shape and volume of the nucleus in the fully grown basal cell of the young gametophyte of Dryopteris filix-mas has been investigated. In blue light the nuclei are more or less spherical, in red and in darkness they are spindle shaped. If the light quality is changed the shape of the nuclei is only slightly influenced; the nuclear volume, however, is drastically changed: increase of volume in the blue, decrease of nuclear volume in red and darkness. These reversible changes of nuclear volume under the influence of light, which are apparently correlated with changing rates of protein synthesis, are an impressive example for the control of nuclear properties by an external factor via the cytoplasm.

— In polarotropism of the chloronema of the fern Dryopteris filix-mas (L.) Schott and of the germ tube of the liverwort Sphaerocarpos donnellii Aust. a phytochrome action in blue and u.v. was presumed[1, 2]. In the present paper this assumption was tested by simultaneously irradiating with red and blue, and red and near u.v. Red energy is given to shift the phytochrome photoequilibrium in favour of high Pfr/Ptotal concentrations. The data obtained by simultaneous irradiation are consistent with the predictions made under the assumption of a phytochrome involvement in the blue- and u.v.-mediated polarotropic response.

1926. Meristeme. Linsbauer's Handb. Pflanzenanatomie. IV. Berlin. SCHWARZ, W. 1927. Die Entwicklung des Blattes bei Plectranthus fruticosus und Ligustrum vulgare und die Theorie der Periklinalchimaren. Planta 3: 499-526. SIFTON, H. B. 1944. Developmental morphology of vascular plants. The New Phytol. 43: 87-129. SNOW, MARY, AND R. SNOW. 1947. On the determination of leaves. The New Phytol. 46: 5-19. SONTAG, P. 1887. Ueber Dauer des Scheitelwachsthums und Entwicklungsgeschichte des Blattes. Jahr. Wiss. Bot. 18: 236-262. SPROTTE, K. 1940. Untersuchungen fiber Wachstum und Nervatur der Fruchtblatter. Bot. Arch. 40: 463-506. THIELKE, CHARLOTTE. 1948a. Beitrage zur Entwicklungsgeschichte und zur Physiologie panaschierter Blatter. Planta 36: 2-33. 1948b. Beitrage zur Entwicklungsgeschichte unifazialer Blatter. Planta 36: 154-177. TROLL, W. 1939. Vergleichende morphologie der h6heren Pflanzen. Bd. I T. II. Berlin. WARDLAW, C. W. 1947. Tensile stress as a factor in fern phyllotaxis. Nature 160: 678. . 1948a. Experimental and analytical studies of pteridophytes. XIII. On the shoot apex in a tree fern, Cyatheca Manniana Hooker. Ann. Bot. N. S. 12: 371384. . 1948b. Experimental and analytical studies of pteridophytes. XI. Preliminary observation on tensile stress as a factor in fern phyllotaxis. Ann. Bot. N. S. 11: 97. . 1949. Experimental and analytical studies of Pteridophytes. XIV. Leaf formation and phyllotaxis in Dryopteris aristata. Druce. Ann. Bot. N. S. 13: 163-198. WEIDT, E. 1935. Die Entwicklung der Blatter der Melastomataceen Heterotrichum macrodon Planch. und Clidemia hirta Don. Beitr. Biol. Pflanz. 23: 252-281.

Summary Apical size, phyllotaxis index and the rate of leaf inception were compared in spiral and bijugate specimens of Dryopteris from the same collection and were found to be similar. Apices were laid bare and maintained under observation in the laboratory for periods of up to 9 months; during this time the bijugate specimens became spiral, as previously reported. Exploratory experiments on the bijugate genus Dipsacus indicate that treatment with gibberellic acid leads to increased internodal elongation and a slight increase in the mean angle of divergence. Removal of young developing leaves and leaf primordia leads to an increase in the rates of leaf inception and development. These observations are discussed in relation to the earlier observations and experiments of Snow. The conclusion is reached that while apices with different systems of phyllotaxis may be of similar size and have similar rates of leaf formation and radial growth, progressive changes in various rates of growth may nevertheless lead to changes in phyllotaxis by modifying the relationships between successive leaf primordia. Vertical as well as radial and tangential growth should be taken into account.

The spores of five taxa of North American Dryopteris were studied with the scanning electron microscope. The taxa considered were two eastern diploids, D. intermedia (Muhl. ex Willd.) A. Gray and the eastern diploid of D. "dilatata”; two tetraploids, D. spinulosa (O. F. Muell.) Watt and D. campyloptera Clarkson; and one western diploid, D. assimilis S. Walker. All the taxa have spores with spines. Spine density and spine morphology are variable both within and between taxa and do not allow a clear identification of taxa using these characters alone. It is considered that all five taxa are closely related as evidenced by the similarities in their perine morphology as compared with species outside the complex.

A B S T R A C T Two types of pteridophylls are very common in the Mesozoic era: the Polypodium and the Dipteridaceae. The Polypodium-type formed by pendulous overtopping is represented in the Mesozoic era by the form-genus Cladophlebis, in the Paleozoic era by the form-genus Pecopteris, and today by Dryopteris. Overtopping differs in these three pteridophylls. Nearly all Paleozoic pteridophylls show a catadromic structure. Today pteridophylls with anadromic and combined catadromic/anadromic structures are the dominant ones. The Mesozoic genera demonstrate a transitional structure: catadromic structures are still frequent, but equally frequent are combined catadromic/anadromic structures. Pteridophylls solely with anadromic structures are unknown in the Mesozoic era. The Dipteridaceae-type is almost exclusively Mesozoic. It is primitive in the dichotomy of the rachis, but advanced in that it is net-veined. Thus the Mesozoic pteridophylls represent connecting links between Paleozoic and recent leaf-types. This nature of Mesozoic pteridophylls can be understood only on the basis of the telome theory. THE MESOZOIC PTERIDOPHYLLS represent morphologically and in time sequence a link between the Paleozoic pteridophylls and those of today. In the Mesozoic they play a role similar to that of the earlier Paleozoic pteridophylls (Zimmermann, 1966). These Paleozoic pteridophy]ls are a link between the early Devonian land plants (Rhyniales) which are still thalloid and the more recent pteridophylls. Thus during the last three billion (109) years a continuous semiphyletic line of plants leads to the development of recent ferns

SUMMARY Six monolayer tissues from various plants were studied for the number of anticlinal walls of non-marginal, unspecialized cells. One class of tissues, including the abaxial epidermis of the scale of Allium cepa, the adaxial epidermis of the leaf of Euonymus fortunei var. vegetus, gametophytic cells of Dryopteris filix-mas, and the surface cells of the bud of Anacharis demo, is characterized by (a) a probability distribution curve with a peak at six walls having a frequency of around 0.40, and (b) tissue growth in two directions. A second class of tissues has the distribution peak of six walls at an approximate frequency of 0.58 and is formed by growth in either one dimension or with regular alternation in two directions, as in the leaf of Anacharis densa and for the colony of Volvox aureus. Models for both classes of tissues were constructed in order to identify those features associated with tissue proliferation that contribute to the variability of cell geometry. Geometric models give a pictorial representation of cell arrangement and are useful in ascertaining cell division patterns whereas algebraic models aid in clarifying spatial relationships between cells. The distinction between packing types and developmental types of models is discussed in the light of the concept of form in plant morphology.

Chromatographic analyses of the phloroglucinol derivatives of 86 collections comprising Dryopteris filix-mas (L.) Schott (4x), D. arguta (Kaulf.) Watt (2x), D. marginalis (L.) A. Gray (2x), and the hybrids D. filix-mas × marginalis (3x), D. cristata × marginalis (3x), D. goldiana × marginalis (2x), and D. intermedia × marginalis (2x) in North America is presented. Material of D. filix-mas from the West differed from that collected in the East. The western material was rich in filixic acid, and had a chromatographic spectrum similar to European D. filix-mas s. str. D. marginalis is lacking filixic acid, and is not closely related to D. filix-mas based on chromatographic evidence. Methylene-bisaspidinol, a compound not previously found in Dryopteris, was isolated from D. marginalis. D. arguta contains filixic acid, and has a chromatographic pattern close to that of D. abbreviata (DC.) Newman, which in turn is one of the ancestors of D. filix-mas s. str. in Europe. The influence of D. marginalis in the phloroglucinol spectrum of the interspecific hybrids studied was very strong except in the hybrid D. filix-mas × marginalis.

The cytology and distribution, together with some morphological notes and a key, are given for nine species of Dryopteris (wood ferns) in Ontario. The cytological determinations were made on 239 plants of nine species, considered as five diploid species (x = 41) (D. marginalis, D. fragrans, D. goldiana, D. dilatata, and D. intermedia), three tetraploids (n = 82) (D. spinulosa, D. cristata, and D. filix-mas), and one hexaploid (n = 123) (D. clintoniana).

Both fresh and acetolysed exines of some species (of Lycopodium, Dryopteris, Stylites, and Betula) have been investigated with the polarizing microscope. The following results were obtained: 1. Sporopollenine is isotropic, as far as investigated. 2. The exine does not show any intrinsic birefringence; it contains therefore neither cellulose nor wax in any considerable amount. 3. The exines of all investigated spores and pollen grains show a birefringence of form (textural bir.), due to a very finely layered structure. This indicates, that not only exines, which are found to be layered in the electron microscope (e. g. Lycopodium), but also “amorphous” ones (e.g. Betula) have the character of a layered composite body.

'WALKER, S. (U. Liverpool, England.) The problem of Dryopteris leedsii. Amer. Jour. Bot. 49(9): 971-974. Illus. 1962.-Investigation of 12 plants of 'Dryopteris leedsii' from the type locality in Harford County, Maryland, has revealed 3 cytological entities, diploid, triploid and t*etraploid. The diploid and triploid types exhibit hybrid characters and are sterile, while the tetraploid is a fertile species. The relationship between the 3 entities remains a problem, but the possibilities are discussed.

Morphogenesis and differentiation of the young gametophytes (=sporelings) of Dryopteris filix-mas are controlled by light. Blue light leads to the formation of “normal” two-dimensional prothallia; under red light, however, the gametophytes grow as cellular filaments. Morphogenesis in blue light is connected with an increase in protein synthesis; in red light the protein content of the sporelings is markedly lower. The size of the chloroplasts is correlated with the protein content of the sporelings. In the present paper the diverse effect of chloramphenicol (CAP) and actidione (cycloheximide, ACT) was studied in connection with the formation of chloroplasts. ACT blocks the growth of the gametophytes, while the chloroplasts remain functional. On the other hand, CAP does not influence morphogenesis of the gametophytes. In particular the activity of the dividing apical cells remains untouched. Even when the light quality is changed during the development the corresponding specific effect of the light quality on morphogenesis is normal. The chloroplasts, however, become smaller, probably by inhibition of synthesis of structural proteins. But their synthetic activity is not completely suppressed. The specific blue or red light dependent morphogenesis is not changed, when protein synthesis in the chloroplasts is inhibited.

Among the eight species of the fern genus Dryopteris which have been recorded from Kenya (East Africa), the group of D. inacqualis, D. pentheri and D. schimperana is regarded as critical. There is no agreement among experts as to whether D. inaequalis s. str. is restricted to South Africa and whether it should be separated specifically from D. pentheri Chemical and, as far as possible, cytological investigations of available material showed that the following taxa of Dryopteris occur in Kenya (ploidy in brackets) : 1. D. athamantica (2 × );2. D. callolepis (4 × ); 3. D. inaequalis (4 × ); 4. D. kilenzensis (2 × ); 5. D. manniana (4 × ); 6. D. pentheri (2 × ); 7. D. schimperana (2 × ); 8. D. sp. RBF-71/885 (TR-330.5) (4 × ); 9. D. squamiseta(ploidy not determined). The nomenclature of the four critical taxa, 3, 6, 7 and 8 is provisional. For comparison, two taxa from the Canary Islands, 10. D. ‘dilatata’ (4 × ) and 11. D. oligodonta (2 × ) were also investigated. Among the nine taxa from Kcnya, two (4 and 9) did not contain any phloroglucides. Dryopteris kilomensis must be regarded as one of the few representatives of the genus Dryopteris which lacks such compounds. On the other hand, the negative result for 9 is in agreement with the fact that this species has recently been transferred to a new genus Nothopevanema. The following three new compounds havc been isolated: Trisaspidinol (8), from D. inaequalis; Pentherin-I (not quitc pure) and Pentherin-I1 (hypothetical partial formula 25), from D. pentheri. Pentherin-I is also present in D. sp. RBF-71/885. Chemical and cytological results are compatiblc with the hypothesis that the latter is an allotetraploid derived from the diploids 6 and 7. The chemical patterns of 6, 7 and 8 show similarities to that of D. manniana, which in turn also shows similarities to the European D. filix-mas. Dryopteris ‘dilatata’ from the Canary Islands is chemically different from Europcan D. dilatata s. str. in lacking para-aspidin, while D. oligodonta gave results rather different from D. inaequalis or other East African species, and also from known European taxa.

Se describe y se compara la morfogénesis de la fase sexual de seis especies de Dryopteris. Las esporas son monoletes, elipsoidales con perina de color pardo a pardo obscuro, su superficie es rugosa de contornos tuberculados y la perina en forma de pliegues. El patrón de germinación en todas las especies es tipo Vittaria y el desarrollo protálico tipo Aspidium. Los gametangios son del tipo común de los helechos leptosporangiados del tipo avanzado, los cuellos de los arquegonios tienen cuatro hileras de células con 4 a 5 células cada una, se forman entre los 53-218 días. Los anteridios de las seis especies se formaron entre los 46-234 días después de sembradas las esporas y tienen 3 células que rodean a la célula androgénica. Los esporofitos se formaron entre los 60-262 días después de sembradas las esporas, como producto de la fecundación en D. cinnamomea, D. karwinskyana, D. maxonii y, D. rossii y son de origen apogámico en D. munchii y D. wallichiana.

The gametophyte differentiation of a fern Dryopteris erythrosora has been investigated in relation to the behavior of ribonucleic acid (RNA). It has been found that two-dimensional growth was specifically inhibited with 8-azaguanine. In parallel to the inhibition, the analog was found to incorporate into RNA, when tested with C 14 -8-azaguanine. The study of changes in the RNA content during the gametophyte development has demonstrated no simple correlation of over-all concentration of RNA or of the rate of increase of RNA to the mode of growth. Conversion of the two-dimensional growth to the one-dimensional growth by the action of 8-azaguanine is followed by a cessation of increase in the RNA content or by degradation of RNA. Finally, it has been shown that RNA from the prothallium in the two-dimensional growth possesses a nucleotide composition distinct from that in the one-dimensional growth. RNA found in the prothallium in the one-dimensional growth induced artificially by 8-azaguanine has been shown to have practically the same nucleotide composition as that of the primary one-dimensional growth. From these observations, it has been tentatively inferred that a special RNA fraction which is sensitive to the action of 8-azaguanine is closely related to the two-dimensional growth.

SUMMARY 1 Interspecific hybrids have been set up between a diploid species of Cydosorus from Ceylon provisionally identified as C. repandulus and three tetraploid species, namely C. dentatus from Madeira, C. parasiticus from Ceylon (two forms), and C. svbpvbescens from Singapore. 2 Interspecific hybrids have been set up between certain pairs of tetraploid species, namely C. svhpubescens (Singapore) x C. sumatranus (Singapore); C. sumatranus (Singapore) x C. jacuhsus (Ceylon); C. jaculosus (Ceylon) x C. subpubescens (Singapore). 3 In morphology these F1 hybrids both triploid and tetraploid showed complete dominance in the expression of some of the morphological characters in which the parents differ and an intermediate condition in others. The more important characters showing dominance were: creeping rhizome versus erect rhizome, presence of anthocyanin pigment on the rachis versus absence of it, uniform length of the lower pinnae versus gradual reduction in length, presence of glands versus absence of these. The more important characters in which simple dominance was not displayed (i.e. F1 hybrids were intermediate between the two parental types) were: depth of cutting of the pinnae, number of anastomosing veins at the base of the pinna segments (in old plants, cf. footnote to p. 737), length of hairs on the lower surface of the stipe. 4 All the hybrids obtained, both triploid and tetraploid, showed a high proportion of aborted spores consequent on irregular meiosis. This was clearly evident even in cases where a preponderance of recessive characters in one parent resulted in a hybrid showing a very close morphological resemblance to the other parent. Spore sterility would therefore be an effective means of detecting hybridity in a herbarium specimen. 5 Chromosome pairing at meiosis has been investigated in all these hybrids in a preliminary way. All show numerous unpaired chromosomes as one factor contributing to spore abortion. In addition, the triploid between C. repandvlus (Ceylon) and C. dentaius (Madeira) showed few or no pairs, indicating rather remote relationship between these two species. The other triploids involving C. repandvlus with C. parasiticus and C. subpubescens respectively all showed approximately equal numbers of pairs and univalents, suggesting that the repandvlus genome is represented in each of the two tetraploid species as half the nuclear content. Among the tetraploid hybrids pairing approximating to n pairs and 2n univalents was found in each of the two combinations C. subpubescens x C. sumatranus and C. sumatranus x C. jaculosus, suggesting that in each of these pairs of species a diploid ancestor is shared. This ancestor could be C. repandvlus in one or both cases, though the evidence is insufficient to determine this. 6 Present knowledge of the ecology and geographical distribution of C. repandvlus is outlined and a method is suggested for searching for the possible existence of other diploids not yet identified. 7 A comparison is made between the C. parasiticus complex in the oriental tropics and the situation already partially elucidated by other workers on the Dryopteris spinvlosa complex in Europe. The resemblance is so close that it seems likely that there are factors operating in tropical floras which are at least as powerful though necessarily somewhat different in kind from those associated with the succession of glacial and inter-glacial conditions which have so strongly influenced the evolution of floras in temperate regions.

— The dose response behaviour for polarotropism of the chloronema of the fern Dryopteris filix-mas was studied in detail. By varying the two factors, time and intensity, dose response curves were obtained, which consisted of as many as two maxima and minima or no maxima and minima at all. Furthermore, the effects of red light and dark, given before polarotropic induction, were compared, and the influence of temperature on the dose response behaviour was examined. There are two main results: (1) Under all conditions tested, the dose response behaviour in far-red, red, blue, and near U.V. apparently is the same. (2) In this one system, the chloronema of Dryopteris, all types of dose response curves, which have been described previously for tropic responses mediated by light, could be obtained simply by varying the conditions. The variable and complex dose response behaviour is discussed in connection with other photoresponses in lower and higher plants.

The effect of desaspidin, ortho-desaspidin, flavaspidic acid, nor-flavaspidic acid and desaspidinol on respiration and oxidative phosphorylation in rat liver mitochondria was studied. All these substances uncouple oxidative phosphorylation. Desaspidin and orthodesaspidin show maximum activity in the concentration 2–4 × 10 −6 M, the other substances in concentrations of 1.6–6.4 × 10 −5 M. Respiration is inhibited more or less distinctly by these concentrations, especially when glutamate or succinate are used as substrate. When pyruvate and malate are employed as the substrate, this effect is less pronounced. In a medium free of terminal phosphate acceptor respiration is stimulated by desaspidin and by flavaspidic acid to values corresponding to those obtained with phosphate acceptor or with 2:4-dinitrophenol. The connection between chemical structure and uncoupling effect as well as the possible connection between the former and the biological effects of the substances tested are discussed briefly.