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Embryos of Rana temporaria have been dissected and shape alterations of different parts of the embryo, taking place within 1 h of separation, have been studied. Two categories of deformation have been revealed. The first category comprises those deformations which take place immediately after separation. They are insensitive to cooling, cyanide and Cytochalasin B treatment. These deformations, which consist of a shortening of initially elongated cells, are considered to be the passive relaxations of previously established elastic tensile stresses. Deformations of the second category proceed more slowly. They are inhibited by cooling, cyanide and Cytochalasin B treatment, are accompanied by elongation and migration of cells and occasionally lead to rather complex morphodifferentiations of isolated fragments. These processes are considered to be the result of the active work of intracellular contractile systems, either pre-existing or induced de novo. By analysing the arrangement of the passive deformations we have constructed maps of mechanical stresses in embryos from late blastula up to the early tail-bud stage. At several embryonic stages drastic transformations of the stress pattern occur, these transformations being separated by periods during which the pattern of stress distribution remains topologically constant. A correlation between the arrangement of stress lines and the presumptive morphological pattern of the embryo is pointed out. Some possible relations between tensile tissue stresses and active mechanochemical processes are discussed.

The study develops a morphological method of assessing the amount of parental components in a U.S. Negro-White Hybrid sample and tests to what extent a multivariate discriminant analysis actually reflects the morphological pattern of hybridization. To formulate norms of description for the parental and hybrid populations, a seventeenth century London Farringdon Street series of 94 crania was selected to represent the British White ancestral component and the data on the cadaverand-skeletal series in the T. W. Todd collection of Western Reserve University, Cleveland, Ohio, were used in the selection of 115 Unmixed Negro and 115 Negro-White Hybrid male crania. The conclusions are: (1) the morphological scores of the Negro-White Hybrid series shows a biological overlap with the two parental series in the proportion of 1:3 (i.e., 25% White to 75% Negro). This overlap reflects the probable porportion of ancestral mixture in the ratio of one-fourth White to three-fourths Negro in the Negro-White Hybrid sample; and (2) the morphological approach to the assessment of the parental components with multivariate discriminant analysis as a tool, proves to be highly reliable in providing a biologically meaningful index of relationship.

A form of cellular degeneration in the fresh-water hydra Pelmatohydra pseudoligactis Hyman is described, and its relationship to the depression phenomenon is discussed. The normal ultrastructure of characteristic cell types in each of the two epithelia (ectoderm and endoderm) is presented; the progress of degeneration is followed through successive stages in an attempt to ascertain the morphological pattern of this abnormal condition. The type of deterioration described shows some similarity to, but appears to be basically different from the phenomenon known as “depression”.

Studies have been undertaken to establish the growth behavior of A. globi-formis in liquid media of different nutritional levels. It has been found that this organism exhibits a distinct morphological pattern during the growth cycle. Cells reached maximum size just prior to division and at this time the pleomorphic forms typical of the genus Arthrobacter were observed. In a simple basal salts medium cells doubled in size while in a complex synthetic medium an 8-to 10-fold increase in cell size was noted during the predivision lag. After the lag period successive divisions occurred with a gradual decrease in size until the cells finally reverted to the normal coccoid form.

Clinical observations show that the morphological pattern of carcinoma at its advancing margin is an indication of its growth potential and is related to the prognosis of the patient. As an experimental approach to the factors determining the growth pattern of carcinoma, three transplantable mouse tumors (a spontaneous CM mammary carcinoma, Bashford carcinoma 63 and Ehrlich ascites tumor) were observed for their growth in the subcutaneous tissue of untreated recipients and of those treated with typhoid vaccine, prednisolone or chloroquine. In the untreated animals, each of these tumors exhibited a specific pattern of the advancing margin, the tendency toward infiltrative growth being greatest in Ehrlich ascites tumor and least in the mammary carcinoma. But, common to these three tumors, the treatment with typhoid vaccine led to a less infiltrating tendency of the advancing margin, as evidenced by better defined tumor boundaries and development of thicker and denser peritumoral connective tissues, and those with prednisolone or chloroquine to a little more infiltrating tendency than in the control. This suggests that the morphological pattern of tumor growth is not fully inherent to each tumor but subject to considerable change according to the condition of the host, probably reflecting the activity of the reticuloendothelial system.

The clinical and pathological features of 26 neoplasms derived from ovarian stroma of canine species were analysed. Three types were identified: (1) granulosa tumours, (2) neoplasms with a Sertoli pattern, and (3) a heterogeneous group regarded simply as nonspecific gonadal stromal tumours. All three types of neoplasm were found in mature dogs. Hyperoestrinising effects occurred in five animals (33 per cent.) of the granulosa group, three (50 per cent.) with Sertoli tumours and four (80 per cent.) of those with nonspecific gonadal stromal tumours. Granulosa tumours were clearly malignant, as three (20 per cent.) had spread beyond the ovary, in contrast to the neoplasms of the other two groups, none of which had metastasised. Tumours with a Sertoli pattern were closely related to granulosa tumours, as they were composed of cells similar to granulosa cells at the periphery of developing follicles and within some atretic follicles of the canine ovary. There were also overlapping patterns with granulosa tumours. Leydig cells and androgenic effects were absent. The neoplasms in this study were compared with tumours of other mammalian species from the standpoint of frequency, morphological pattern and behaviour.

Crown characters of the deciduous dentition in the Japanese-American hybrids were compared with those of their parental populations in the light of character complex, or morphological pattern characterizing the Mongoloid as well as Caucasoid populations.In the hybrid groups, both Japanese-Whites and Japanese-Negroes, the frequency distributions of the crown characters generally show intermediate patterns between the parental populations. At the same time, the differences that originally exist between the paternal populations, or American Whites and Negroes, are repeated in those between both hybrid groups. This is likely to suggest thatthe crown characters here discussed are controlled by relatively simple genetic factors.The mean value of the canine breadth index in the Japanese-Whites, on the other hand, is quite different from that of the American Whites and falls well within the range of the non-White populations. The same trend is also observed in the other cases of race mixtures between White and colored populations. This fact may prove that the canine breadth index is determined under the control of relatively complicated genetic factors.As a whole, though the hybrids show peculiar features to themselves, there is no evidence of disharmonious combination of characters, at least the crown characters under discussion are concerned.

The morphology of the duodenal mucosal surface of chickens infected with Eimeria acervulina has been studied on days 5, 6, 8 and 11 post-infection and compared with that of the normal duodenal mucosa using the scanning electron microscope. The normal duodenum possessed tall, spatulate villi with horizontally-arranged surface clefts upon which a regular pattern of hexagonal absorptive cells and goblet cell mouths was superimposed.A maximum degree of villous atrophy was shown on day 5 post-infection, the villi being thickened and flattened with frequent adhesions and fusions between them. The general effects of the disease together with the physical presence of intracellular parasites caused considerable changes in size and shape of the cell apices. By day 8 the mucosa was clearly recovering, with a normal pattern of somewhat thickened and truncated villi beginning to re-appear and by day 11 post-infection the mucosa had regained an outwardly normal morphological pattern. The mucosal changes are discussed in relation to similar changes which occur in diseases of the alimentary tract of other animals, including man.

The effects of the administration of methotrexate to rats at different oral doses has been studied. The administration of a single dose of 6 mg kg provokes little response from the intestine; no morphological alterations could be detected, and only marginal changes in absorptive capacity were perceived. However, the ingestion of a sub-lethal dose (40 mg kg ) induces serious lesions of the intestinal mucosa by arresting cellular regeneration in the crypts. In spite of the morphological damage, the active absorption of amino-acid persists, albeit at a reduced level, until nearly all the mucosal surface has been desquamated. However, when a certain level of destruction has been sustained, the function falls suddenly to zero. The metabolic activity of the mucosa, as witnessed by respiration, glucose consumption, and lactic acid production, reflects the changes in absorptive capacity. Successive daily administrations of the drug at the lower level eventually induce the same changes that occur after a single high dose. The ingestion of this drug has provided an excellent model by which the functional activity of the intestinal mucosa can be correlated with the histological findings. Two cases are presented where the morphological pattern would not predict the state of functional viability of the tissue. After 48 and 96 hr, following the administration of a single high dose of methotrexate, there is extensive and severe mucosal derangement, but sometimes a considerable though depressed transport capacity is maintained. On the other hand, rats surviving the high dose of methotrexate have a normal histological pattern after 8 days, though their functional activity is still depressed. These findings suggest that clinical studies on intestinal biopsy samples should include functional tests as well as histological examinations whenever possible.

This report is concerned with light microscopic and, especially, electron microscopic changes taking place under the influence of Crasnitin 1 in laboratory animals and in vitro. The only morphological findings so far available are those of Borella et al. (1966) on ascitic cells in a case of lymphosarcoma. The guinea-pig-L-asparaginase which they used failed to produce significant effects on the lymphosarcoma cells examined. Our studies of the morphological pattern were intended to provide insight into the possible mechanism by which L-asparaginase acts on cells and tissues.

A SYSTEMATIC study of the morphology and function of the visual mechanism in the vertebrates reveals a variation in visual capacity and a wide alteration in the optic centers of the brain due to the development and elaboration of addition structures. On the other hand, the general morphological pattern of the eye as a whole or of its parts is quite similar in all these animals. This is particularly true when we consider certain features of that essential delicate membrane the retina, upon which many of the following experiments are focused. In all vertebrate eyes a prominent pigment epithelium marks the basal layer of the retina, above which lie the three characteristic nuclear layers, namely, the rodcone elements, the intermediate bipolar cells, and the ganglion cells. Lacking a better term, I shall identify these layers, along with their intervening reticular zones and the inner and outer membranes, as the neural

The history of English since 1050 may be regarded as consisting of two periods with the year 1300 as a very rough terminus ad quem for the first and terminus a quo for the second. The period from 1300 to the present has been characterised by very extensive changes in the phonetic form of English and by important syntactic changes but not by correspondingly great changes in the morphological pattern of English speech. The morphological changes in nouns and adjectives have been almost wholly the result of the loss of final e and to a very small extent the result of analogical processes. Analogical processes have resulted in important changes in the inflectional pattern of verbs but in verbs also changes in morphological structure have been to a much greater extent the result of other causes, especially the displacement of forms ending in -en by forms ending in e and the subsequent loss of final e.

The early growth in culture medium of newly isolated blood forms of different Trypanosoma cruzi strains has been studied. Trypanosomes of three strains regularly change into leishmanoid forms that undergo further divisions under this form and then give origin to large colonies of round parasites. These colonies are gradually replaced by typical crithidia both free and in rosettes. Blood forms from two other strains soon change into crithidia, leishmanoids being observed only rarely. There is some evidence that this different behavior in culture depends on the morphological pattern of the blood forms from the several strains. The possibility of the action of a specific antibody is discussed. In a previous paper, Brener and Chiari (1963) reported a morphological study of T. cruzi blood forms of seven different strains that had been kept in experimentally infected mice. In the present paper we have studied the early growth in culture medium of the blood forms from the seven strains with the purpose of relating some aspects found in culture with the morphology of the blood