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This article is concerned with the electronic transport properties of the large group of solids (and also some liquids) which possess carrier mobilities from 10 cm2V-1sec-1 to many orders below that value. Its main aim is to trace the close relation between transport and localization. To this end the physical basis of three important localization models is discussed and the predicted transport mechanisms are reviewed in the light of the experimental information. After a brief summary of the experimental methods, the first subject is the localization arising from strong electron-phonon interaction. Here we consider in some detail the formation of a small polaron in a molecular crystal and its transport by phonon-assisted intermolecular hopping. The second part of the paper deals with the localization of an electron in a so-called electronic bubble, which occurs for example in simple liquids such as Ne or He. The stability and transport of this entity is discussed. The third section is devoted to non-crystalline solids. In these localization is associated with the lack of long-range order and does not depend on phonon interaction. The transport through the various parts of the density of states spectrum is summarized and the suggested models are reviewed on the basis of recent experimental work on amorphous silicon. Finally, the possibility of polaron formation and transport in some chalcogenide alloy glasses is briefly considered. The paper leads to the conclusion that available experimental evidence supports the general validity of the above three models, although it must be emphasized that this is based on an as yet limited range of experimental information.

An interview with American painter William Traher is presented. He discusses his special training in painting a diorama background. He details his approach in the effective use of rollers, sponges and paint spray guns in his murals. He also share some of the details about the layer-on-layer painting technique.

The article details the author's conversation with American painter Jacqui Morgan. She discusses her hectic activities, which include doing an image for an illustration and making designs for clothing. She explains the differences between an illustrator and a painter. She also shares the challenges she is facing as a woman artist especially in reconciling her career with her private life.

The article presents questions and answers related to painting including how to protect the rear of an oil painting, the possibility of using an old paint and the use of a fluid oil paint on imported rag watercolor paper.

The article elaborates on the approach of American painter Peter Homitzky to industrial landscape painting. The strength of Homitzky's works are dominated by the interaction between mechanical and natural forms. He uses very flat color in painting mechanical structures to emphasize the generalized simplicity of forms. He likes to work on several paintings at a time.

A biography of French-American naturalist painter John James Audubon is presented. He was born in 1785 in the French West Indies to a French naval officer and a Creole woman who died soon after his birth. After a brief stay in military school in France, he studied art under court painter Jean-Jacques David. He has a passion for bird life as illustrated in his work "Birds of America," which was published by London, England-based Havells in 1838. He died in 1851.

The author discusses his approach to watercolor painting of old houses and buildings with an illustration using his work "Requiescat." Before painting, he visits the location of the subject to gather important record of it including its detail. In painting, he uses one-fourth-inch Upson board instead of watercolor paper because it is thicker and dries faster. He prefers to draw the subject on tracing paper and transfer it to the Upson board panel after making some corrections. He believes that patience is an important aspect to his type of painting.

Most studies to date of ethnic relations, ethnic boundaries, and criteria used to define ethnic status have been biased toward a particular “assimilationist” model drawn from experience in North America, Australia, etc. These have generally assumed that there is some dominant or ethnically “neutral” area of culture by whose standards all “ethnics” can be judged, and that ethnic identity normally changes in one direction only. This paper examines the case of a plural society in which there is no clear dominant or neutral culture, and in which continuous oscillation of ethnic status occurs without direct assimilation.

The purpose of this paper is to provide a clarification of the relationship between acculturation and assimilation through the development of a conceptual framework. By means of a careful review of theoretically relevant literature prevalent characteristics related to each concept are delineated and discussed in order to identify and synthesize common, as well as contrasting, elements. A comparison of these elements or characteristics is then undertaken pursuant to proffering a clarification. In short, then, this paper seeks to compare and contrast salient characteristics of the concepts of acculturation and assimilation in order to clarify and delineate the relationship between them.

The use of various preservatives and storage containers for the sampling of urine and water samples for mercury analysis was evaluated. The results indicated that glass storage containers were preferred over paper or plastic containers and that potassium persulfate, when added to the sample at the time of collection, would preserve the sample for several days without significant losses. Potassium permanganate was found to he unacceptable for preserving mercury in aqueous solution because of the formation of insoluble manganese dioxide.

Dermatitis due to handling cement continues to be an occupational problem. This paper describes laboratory and human studies undertaken to determine the content of chromium, cobalt, and nickel in American cement samples and their etiological roles In causing dermatitis observed in cement workers in the United States.

This volume is based on a postgraduate education seminar dealing with new approaches to the understanding and management of learning problems in children, presented by the University of Florida, Gainesville, in 1971. The contributors, mainly from the university, offer a series of papers concerned with the neurology, psychology, or educational aspects of children's learning. Most of the papers have a research design and are clinically applied. A collection of 13 separate presentations, the papers are divided into three major sections: (1) preschool development, (2) problems of early school development, and (3) intervention and outcome.The first chapter I experienced as a pleasant, somewhat wordy, and not particularly useful introduction to the remainder of the book. This was followed by a fine chapter, "Early Brain Damage and Later Development," discussing central nervous system (CNS) structure and the effect of alterations of that structure on subsequent function and development. For the reader

Of the six essays in this symposium report, only two address the topic suggested by the title. J. McV. Hunt presents a convincing, well-ordered review of his theory of "psychological development as a hierarchy of learning sets, strategies of information processing, and skills built one upon another in ordinal fashion," and urges that only a much greater understanding of the details of this structure will fulfill its theoretic promise for application to retarded and normal children. R. P. Toister reviews very briefly some implications of behavior technology for mental retardation.The remainder of the book contains papers only peripherally related to its title: Edward Zigler presents extensive experimental evidence that distorted motivation accounts for part of the poor performance of older retarded children; A. D. Cortazzo urges teachers to pay attention to individual differences; David Elkind describes some differences between lower class and middle class adolescents who produce "borderline

This paper comments on the induction of gametogenesis, on microscopical and electronmicroscopical aspects of spermatogenesis and oogenesis and on fertilization in the genus Hydra. Spermiogenesis does not present any peculiarities. The ripe sperm contains no detectable acrosoinc. Egg-formation involves phagocytosis of entire oogonia by growing oocytes. Several oocytes merge to a single oocyte, in which one nucleus becomes the germinal vesicle. The egg shell is formed only when the egg is fertilized. Various factors such as the synchronization of gametogenesis, the length of sexual periods, continuous release of sperm and the long life span of sperm are considered to guarantee the fertilization of the eggs.

Research on anemone development has been largely descriptive. In this paper I review the work on anemone development and in doing so, attempt to point to areas where additional investigation may prove fruitful. There is only a little information available on gametngenesis and fertilization. Eggs and sperm may be released by the adults with fertilization occuring in the external environment. In other cases females retain the eggs within the gastrovascular cavity or septa until after fertilization. There is some behavior reported to be associated with spawning. Anemone eggs range from 80 to 1,100 µ in diameter. They may have a smooth or a spiny oolemma. The smaller eggs undergo holoblastic cleavage, form a hollow blastula, and gastrulate by invagination. Larger eggs show delayed cytokinesis, superficial cleavage, form a solid blastula, and undergo gastrulation by a confusing variety of methods. Most gastrulae are ciliated and able to swim. Smaller zygotes become hollow planulae which may be planktotrophic or parasitic. Larger zygotes become lecithotrophic larvae which may be free living or brooded in a variety of ways. A general lack of information exists for many families and some conflicting descriptions await further investigation.

An agar diffusion method using paper disks on plates seeded with Clostridium perfringensand incubated anaerobically to assay serum levels of metronidazole is described. The lowest serum metronidazole concentration that could be measured was 0.7 µg/ml, and the average error was 4% for 5 µg/ml. This assay could measure metronidazole in the presence of gentamicin or in the presence of penicillin, with the use of penicillinase incorporated into the assay plates, or in presence of penicillin, methicillin, and cephalothin with prior exposure of the specimen to beta-lactamase.

Digital communication systems using the narrow pulses generated by a mode-locked laser are extremely efficient in their use of average laser power. However, these narrow pulses require precise system timing and decision intervals matched to the pulse width. This paper extends previous work by Gagliardi in this area to consider the effects of pulse timing errors and pulse width mismatch on the probability of bit error for on-off keying, binary pulse position modulation, and quarternary pulse position modulation formats. The general expressions are derived, and a number of examples are plotted.

This paper deals with the investigation of the ray delay in gradient waveguides with any transverse refractive profile. A perturbation method is used for the calculations. It becomes apparent that the delay differences in the pure gradient medium are very small for any decreasing profile and that they are of an order of magnitude of those found in a monomode waveguide (material dispersion). Larger delay differences do, however, occur when the ray paths are to some extent determined by an outer cladding. These influences must be eliminated to allow the excellent delay time properties of a gradient medium to really be utilized.

When the current through the junction of a light emitting diode (LED) is modulated, there is a delay between the modulation and the response of the optical signal to this modulation. We have recently observed that this delay is not the same at different parts of the LED’s optical spectrum. This effect, the relative delay between spectral components, we call chromatic delay. This paper reports the results of measurements of chromatic delay for several LED’s of various kinds. This effect amounts to delays of the order of 200–300 psec between half power points of the LED spectrum. Thus it establishes a lower limit on the rise time achievable from these devices.

This paper describes a single transverse mode Q-switched Nd^3+ glass laser working on a few longitudinal adjacent modes. The narrowing of the spectral output is obtained by use of a resonant reflector and a birefringent filter under temperature control. The number of longitudinal modes is varied from one to ten with a constant energy output of 10 mJ by means of intracavity resonators and two-step Q-switching. Observations of the quasiperiodic intensity fluctuations during the 40-nsec pulse give information about the statistical character of multimode giant pulse laser emission.

This paper is a theoretical presentation of a two wavelength holographic method of measuring the roughness of a surface. This method extends the range of surface roughness which can be measured to arbitrarily rough surfaces. This paper also discusses the factors that limit the accuracy of the proposed method.

This paper describes the design of a two-component grazing-incidence mirror system for use with a grazing-incidence spectrometer in order to record spatially resolved solar spectra in the 150–850-Å region. Photoelectric measurements are presented of the point spread function and reflectivity of the mirror system at discrete wavelengths in the extreme ultraviolet.

The Multispectral Scanner (MSS) was launched on the Earth Resources Technology Satellite (ERTS-1) 23 July 1972. The MSS has two calibration systems, one internal and one external. Both calibration systems have shown strong, spectrally dependent performance degradation since launch. This paper presents details on the optical system of the MSS and data on the performance degradation as a function of both spectral interval and time in orbit. The history of the MSS during tests is traced, and it is shown that hydrocarbons from an external source may have been deposited on optical surfaces in the instrument. It is postulated that these contaminant coatings may have polymerized as a result of the exposure to uv light from the sun, increasing their blue absorbtion and accounting for the observed performance degradation. Arguments supporting this postulate are presented, and other possible sources of the performance degradation are discussed.

A two-dimensional (two-color) statistical structure is formulated that is applicable to pattern recognition, discrimination, and detection problems occurring in infrared signal-processing systems. The methodology relates physical quantities such as the temperature T of an object, its projected area A, emissivity ∊, range R from the sensor, and noise equivalent flux density (NEFD) to the geometry of a local orthogonal coordinate system where the coordinate axes correspond to the apparent radiant intensity J in each micron bandwidth. The bivariate distribution, correlation, and transformation properties attendant to this framework are discussed in detail. Additional insight into the structure of the problem is achieved by investigating the two-color system in terms of a nonorthogonal local coordinate system. The various results presented in the paper may be extended to three-, four-, or five-color systems by direct analogies.

A quantitative method for determining polystyrene in paper sheets was developed. Polystyrene is determined by refluxing the sample with chloroform and ultraviolet measurement of the polymer in the extract. The percentage recovery was compared to the values obtained by a gravimetric procedure using hot chloroform extraction in a Soxhlet apparatus. The values obtained by both methods were found to be in good agreement.

The countertransference hatred (feelings of malice and aversion) that suicidal patients arouse in the psychotherapist is a major obstacle in treatment; its management through full awareness and self-restraint is essential for successful results. The therapist's repression, turning against himself, reaction formation, projection, distortion, and denial of countertransference hatred increase the danger of suicide. Such antitherapeutic stances, their recognition, and the related potential for constructive or destructive action are the subject of this paper.

Considering Walter Kempner's family background, it is not surprising that he chose medical research as a career. By the time of his birth, Jan 25, 1903, both of his parents were active medical investigators. His father made the first antitoxin against the poison of Bacillus botulinus. His mother established the pathogenicity in humans of the bovine strain of Mycobacterium tuberculosis. Both had begun as assistants to Robert Koch, discoverer of the tubercle bacillus. Koch was the godfather of Dr. Kempner's brother who made a name for himself as the American deputy chief counsel in the war crime trials in Nuremberg.Walter Kempner graduated from the Medical School of the University of Heidelberg in Germany in 1926. After internship in Heidelberg, where his first paper, on diabetes, was published, he worked in 1927 to 1928 and again in 1933 to 1934 at the Kaiser Wilhelm Institute for Cellular Physiology in Berlin-Dahlem,

TO THE EDITOR. —In the July 1973 issue of the Archives two articles appear that deal with liver disease, renal transplant patients, and azathioprine. The article by Briggs et al (132:20, 1973) looks at a hepatitis outbreak in the dialysis unit and concludes that "the present study... suggests that it (azathioprine) may have an adverse effect in an already injured liver." The recommendation is made that, in patients who develop hepatitis after transplant, the azathioprine be decreased or discontinued. It was also noted in this study that the hepatitis developing in the immunosuppressed transplant recipient was a mild disease of short duration. The authors speculate that this was possibly due to the steroid therapy the patients were receiving. Does this imply that the steroids were beneficial in altering the acute course of the hepatitis? One might conclude from this paper that, while azathioprine was bad, steroids were useful in the

TO THE EDITOR. —Dr. Koretz has aptly pointed out the major difference of opinion between our two basically dissimilar papers.There is no real difference of opinion regarding the question of primary azathioprine hapatotoxicity. Although this condition probably does exist, there is still no conclusive evidence that it is a major cause of clinical liver disease in kidney transplant recipients. Patients described in our paper and in that of Ireland et al accounted for virtually all instances of recognized liver disease in transplant recipients at one institution over a ten year period; in none could azathioprine be implicated as the primary agent.With regard to Dr. Koretz's question as to whether azathioprine should be continued in the face of acute or chronic hepatic injury, there is a difference of opinion. (I suspect that this difference of opinion is not unique to our institution.) It is not surprising that the liver

Statistics need not be awesome! This is the author's first sentence; she has set out to provide a semiprogrammed self-learning and testing text in order to "guarantee" that the least quantitatively inclined student of medicine will be able to understand statistical statements in the current medical literature and to conduct simple statistical tests.She has done a superb job of implementing these objectives. The mix of topics is excellent. Considered, in addition to the usual subjects of elementary statistics, are "important" vs "statistically significant" differences, the log-transform, use of cumulative probability paper, difference between precision and accuracy, biassay, nonparametric tests, difference between type I and type II errors, and the correct statistical approach to estimating size of sample needed—topics of importance that are ignored in many texts on medical statistics. I would like to have also seen a separate chapter on the clinical trial and discussions of life table survival

This is a collection of 21 reviews published in 273 very expensive pages. Nine papers deal with ovarian tumors; however, they are not comprehensive. The remaining 12 reports are arranged under general headings: four in the "General" category, three under "Diagnosis," one "Chemotherapy Review," and a collection of three articles labeled "Specific Neoplasms." Most are brief and, as far as I could detect, no original material is published.The longest review deals with some studies on serum copper (34 pp) and the shortest (4 pp) with cancer of unknown primaries. As with many books containing progress reports the articles vary greatly in quality and do not cover clinical cancer or clinical cancer research comprehensively. The book would be of little interest to workers in the field of clinical cancer, since much of the material has been widely published and reviewed elsewhere. It should be useful to readers with limited exposure

This volume purports to be a comprehensive review, but it is uneven in the emphasis it gives to various aspects of pain. The quality of the 134 reports by 171 authors, mostly from the European continent, varies widely. Sections on pain measurement, afferent systems, perception, and pain processing in the central nervous system are worthwhile. A skimpy section on psychosomatic aspects of treatment contains four unclear articles emphasizing hypnotherapy and an informative one by H. K. Beecher on the placebo effect. Chronic intractable pain syndromes are incompletely dealt with, mainly in a section on surgical treatment methods.The book is top-heavy with laboratory and clinical studies on pentazocine, an opioid antagonist that possesses analgesic properties. The research design of many of these papers leaves this reader uneasy, and the abuse potential of this drug is passed over lightly.The symposium and its publication were supported by the Winthrop Products Company.

Meeting.—The second annual meeting of the Society for Ear, Nose, and Throat Advances in Children (SENTAC) will be held at the San Francisco Hilton in San Francisco on Oct 18, and 19, 1974, in association with the annual meeting of the AmericanAcademy of Pediatrics. Abstracts or papers of 10 or 20 minutes' duration should be submitted by May 30 to Virgil M. Howie, MD, Program Chairman, 2345 Whitesburg Dr SE, Huntsville, AL 35801. Information concerning registration may also be obtained from Dr. Howie.Postgraduate Course and International Meeting.—A postgraduate course in rhinoplasty will be offered Aug 18-23, 1974, at Odense University Hospital, Odense, Denmark. The International meeting of Rhinology will also take place Aug 23-25, 1974, at Odense University Hospital. For information contact P. Stoksted, MD, ENT Department, Odense University Hospital, DK-5000 Odense, Denmark.Deafness Research Foundation Grants.—The Deafness Research Foundation announces that applications for research grants,

To the Editor.—The August 1972, issue of the Archives included the paper we presented at the Central Surgical Association reporting cases of tracheal innominate artery fistula.1 We cited three reported cases of survival of this catastrophe, published in English, in the American literature, the earliest in 1968. However, one of the members of our clinic, Dr. Michel Roy, published a previous report in French in 1962,2 which makes it the first case of survival of this complication known to us. The following is the translation by Dr. Roy of an abridged version of his case report.A 31-year-old female entered the hospital for a viral encephalomyelitis with progressive ascending paralysis affecting the respiration. A tracheostomy was done at the level of the second tracheal ring. The automatic respirator was connected to the metal tracheal cannula. Two days later, a massive hemorrhage from the neck occurred. The blood

Raymond Plant, Hegel, George Allen & Unwin, London, 1973, $11.30, $6.15 paper.

1. The reaction pathway for the decarboxylation of oxaloacetate, catalysed by pig liver pyruvate carboxylase, was studied in the presence of saturating concentrations of K+ and acetyl-CoA. 2. Free Mg2+ binds to the enzyme in an equilibrium fashion and remains bound during all further catalytic cycles. MgADP− and Pi bind randomly, at equilibrium, followed by the binding of oxaloacetate. Pyruvate is released before the ordered steay-state release of HCO3− and MgATP2−. 3. These results are entirely consistent with studies on the carboxylation of pyruvate presented in the preceding paper (Warren & Tipton, 1974b) and together they allow a quantitative description of the reaction mechanism of pig liver pyruvate carboxylase. 4. In the absence of other substrates of the back reaction pig liver pyruvate carboxylase will decarboxylate oxaloacetate in a manner that is not inhibited by avidin. 5. Reciprocal plots involving oxaloacetate are non-linear curves, which suggest a negatively co-operative interaction between this substrate and the enzyme.

Streptomyces griseustrypsin (S.G.T.) isolated from pronase was reduced, aminoethylated, and digested with trypsin. The soluble peptides were recovered and the insoluble residue redigested with chymotrypsin. Following recovery of the soluble fraction, the insoluble portion was in turn digested with α-lytic protease of Myxobacter495. The three groups of soluble peptides were separately subjected to ion-exchange chromatography on the Technicon peptide analyzer and to final purification by high-voltage paper electrophoresis. Sequence analysis by the dansyl-Edman procedure provided unique sequences from the soluble tryptic peptides accounting for 65% of the S.G.T. molecule. Peptides obtained from the redigests of the insoluble residues accounted for an additional 20%.Tryptic digestion of dansylated S.G.T. yielded a unique α-NH2dansylated peptide whose composition showed it to be the same as the NH2-terminal sequence previously postulated for this enzyme. The tryptic peptides isolated in this work have provided overlaps for many of the previously sequenced peptic peptides. Three continuous sequences of 49, 36, and 28 residues have been elucidated.Evidence has also been obtained that the NH2-terminal valine residue was, to a limited extent, aminoethylated during reaction of the reduced protein with ethylenimine.

1This review covers the Pleistocene history of British non‐marine Pisces, Amphibia, Reptilia and especially Mammalia, which alone have a good fossil record. Aves are also briefly discussed.2The fossil material available is often inadequate for purposes of taxonomy and identification. Further problems arise because many groups of Mammalia have undergone rapid evolution during the Pleistocene.3In this paper the fossil record is related to the currently accepted stratigraphic table of the British Pleistocene (Shotton & West, 1969). Wherever possible, fossil records have been assigned to pollen assemblage zones. Throughout, emphasis is placed on the relationship between faunal history and vegetational history, as determined from fossil pollen and macroscopic plant remains.4Although fossils are relatively scarce in the fluviatile and lacustrine deposits of open sites, compared with the often rich cave assemblages, the stratigraphy of the former is usually much clearer and the sediments commonly contain pollen. It is difficult to correlate cave sequences with those of open sites.5It is important to take into account possible bias in a fossil assemblage according to its mode of accumulation, e.g. assemblages from occupation sites may represent only those animals which were hunted by man.6Lower Pleistocene vertebrates are rather poorly‐known. The majority of fossils are from the marine Crags of East Anglia (Pre‐Ludhamian to Pastonian) and a single cave assemblage of this age is known (Dove Holes). Few records can be related to particular stages, but a few finds from Easton Bavents are assigned to Antian and Baventian stages.7Early Middle Pleistocene vertebrates are represented mainly by the rich assemblages from the marine and fresh‐water Weybourne Crag and Cromer Forest Bed Series (Baventian to Early Anglian) of Norfolk and Suffolk. The East Runton fauna appears to be of pre‐Cromerian (?Pastonian) age. A good fauna is known from the type Cromerian deposits at West Runton (zone Cr 11). A few records are available for zone ?Cr III and one for the Early Anglian. The assemblages from other localities appear to represent more than one stage at each site, e.g. the so‐called ‘Bacton Forest Bed’ fauna is composite, including both Cromerian and ?Pastonian taxa. Outside East Anglia one open site (Sugworth) and one cave fauna (Westbury) of probable Cromerian age are known.8Many of the fossils found in lacustrine and river‐terrace deposits of the Middle and Upper Pleistocene glacial‐interglacial succession (Anglian to present day) can be assigned to particular stages, zones or even subzones. Cave assemblages rarely predate the Ipswichian. No pre‐Devensian records are available for either Scotland or Ireland. The Anglian fauna is very poorly known. The Hoxnian is represented principally by the Clacton (zone Ho IIb) and Swanscombe faunas. The Baker's Hole deposit, the basal gravels of the Summertown‐Radley Terrace and the Glutton and Bear Strata in Tornewton Cave have yielded faunas of probable Wolstonian age. The early Ipswichian is poorly represented (Selsey), many fossils are known from zone Ip Iib (e.g. Trafalgar square, Swanton Morley, Aveley), there are a few records from early zone Ip III (Aveley, Swanton Morley) and fairly good faunas from zone Ip III/IV (Histon Road, Stutton). Several open and cave‐site faunas resemble those of zones Ip II and Ip III and the assemblages from Ilford, Brundon, etc., appear to date from the end of this interglacial. The Early Devensian is represented by the Wretton fauna and probably by some cave faunas. Middle Devensian faunas are fairly well known (e.g. Upton Warren) and there are a number of records for the Late‐Devensian (Ballybetagh, High Furlong, Nazeing). Many cave faunas date from the Middle or Late Devensian. Good faunas are available from the early Flandrian, zone F1 I (e.g. Star Carr). The present‐day native fauna (zone F1 111) is also discussed.9The main faunal characteristics for each subdivision of the Pleistocene are summarized in the Conclusions. There is a major faunal change between the predominantly Tertiary fauna of the Red Crag Nodule Bed (Probably Pre‐Ludhamian and older) and that of the Red Crag (Pre‐Ludhamian and Ludhamian). There appears to have been comparatively little change in fauna through the rest of the Lower Pleistocene but the more intense climatic fluctuations of the Middle and Upper Pleistocene were accompanied by rapid faunal change and the appearance of characteristic ‘steppe‐tundra’ faunas in the Wolstonian and Devensian cold stages. The Late‐Devensian and Flandrian faunas are impoverished in comparison to earlier stages. This may be partly due to the activities of man as well as climatic and vegetational changes.10There is usually good agreement between fauna and vegetational conditions when these can be compared, but a few taxa (e.g. Cricetus cricetus, Equus) have clearly changed their ecological requirements during the Pleistocene. Changes of fauna in response to vegetational changes within interglacials are known from the Hoxnian and especially the Ipswichian. The ‘steppe‐tundra’ vegetation of cold stages was accompanied by a mixture of animals nowadays extinct or living in either steppe or tundra.

A simple and rapid method for the simultaneous quantitative analysis of mixtures of hematoxylin and hematein uses the molar extinction coefficients of the pure substances calculated by Lalor and Martin (1959). Absorbance measurements of the samples dissolved in methanol are made at wavelengths of 292 nm and 445 nm, the wavelengths of maximum absorption of hematoxylin and hematein respectively. The hematoxylin absorbance at 292 nm is corrected for the presence of hematein.Using this method it was found that of 12 commercial samples labelled "hematoxylin" all contained at least 90% of the compound. Hematein contents of these samples fell in the range 0.1% to 6.8%. In 9 commercial samples labelled "hematein" the hematein contents fell in the range 1.2% to 90.7%. The hematoxylin contents of these samples fell in the range of 1.0% to 82.7%.This paper describes also a chromatographic method for the identification of hematein and its oxidation products.

The dexribed technique facilitates oriented embedding of individual cells in various media for both light and electron microscopy. A fixed Specimen is embedded in a small cube of 2% agar at 40 C and subsequently sealed in the desired orientation to a strip of black paper which then serves as a tab for transferring the specimen during dehydrating and embedding procedures. The beveled ends of the strip indicate the exact location of the specimen in the cube. This technique can be employed for the embedding media used in both light and electron microscopy. It ah permits photomicrographs of the whole specimen to be made which can be compared with photomicrographs of individual sections cut from the specimen in a selected plane.