Neurulation in the Teleost, Oryzias latipes, was characterized by the formation of a solid neural cord (keel) unlike that in other vertebrates. The cord cells then divided into right and left groups adjacent to the midline, and finally formed a pseudostratified epithelium on each side. In the midline, the primitive neurocoel first appeared in the ventral part, and then gradually dilated and extended dorsad. Around the time of appearance of the neurocoel, the following remarkable morphological changes were encountered in the neuroepithelial cells: marked elongation of each cell; a desmosomal connection between cell necks near the apical cell surface; irregular apical cytoplasmic projec tions into the neurocoel. It may indicate that these morphological changes play a role in the opening of the neurocoel.
Neural crest cells were derived from th e ectoderm, and were, at first, intercalated in the space between the dorsal end of the developing neural cord and the epidermis in a wedge-like fashion, and then followed by gradual separation. These cells were irregular and somewhat amoeboid in shape, suggesting an active migration.
Comparison of the process of neural tube fo r mation and of neural crest separation in teleosts with these processes in other vertebrates, suggested that there were little essential differences in the morphogenetic events involved.

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Applying silver impregnatio n methods, the long ascending fibers from the spinal cord were reclassified according to the location of degenerating fibers in the brain stem as a result of lesions in the spinal cord in the rabbit, rat and cat. In the bulb, the long ascending fiber systems ascended in the medial lemniscus and lateral to it, and at the level of the trapezoid body diverged into following fiber system: The lateral thalamic system and ventral thalamic system ran through the medial lemniscus, and the former terminated in the posterior ventral nucleus and the latter terminated in the zona incerta, Forel's H-field and posterior hypothalamic area. The FR-system ascended through the reticular formation and terminated in it, and the GM-system ascended medial to the brachium of the inferior colliculus to reach the medial part of the medial geniculate body. Some fibers of these two system interweaving with each other in the rostral mesencephalic reticular formation made up the medial thalamic system which terminated in the internal medullary lamina and its associated nuclei (parafascicular and lateral central nuclei). The spinotectal system terminated in the superior colliculus and passed through it. Further, there occured the fibers terminating in the periaqueductal gray matter and passing through it.
Terminals in the posterior ventral nucleus were observed following the all spinal lesions in the rabbit and rat, and in the cat numerously after the first two cervical lesions and scarcely after the oth er cervical and upper thoracic ones. In the cat, probably in the rat, some fibers of the lateral thalamic system terminated in the lateral ventral nucleus.
Development of the medial thalamic system was most prominent in the cat and least prominent in the rabbit in three species. Degenerating fibers in the internal medullary lamina and its associated nuclei were scarce in the rabbit following the uppermost thoracic lesion and not so much degeneration was found even after the uppermost cervical lesion. These degenerating fibers in the rat were slightly more following a lower thoracic injury than those in the rabbit with some cervical lesion, and were not found with the uppermost sacral one. On the other hand, in the cat even following the fourth lumbar lesion, preterminals in the lateral central nucleus appeared clearly.

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Spermiogenesis of the dom e stic pigeon Columba livia domestica L. has been studied with the electron microscope. The proacrosomal granule occurring in the Golgi complex is well situated at the anterior pole of the spermatid nucleus. It was noticed that no electron-lucent acrosomal vesicle is visible during the formation of acrosome. Cytoplasmic microtubules appear originated from the amorphous or fibrillar material attached to an irregularly spaced, double-layered nuclear envelope. In correspondence with the appearance of microtubules there occurs the chromatin aggregation in the elongating nucleus. The tubular body has been found for the first time in the domestic pigeon spermatid so far as avian spermatids are concerned. The tubular body involving ribosomes may contribute to the protein synthesis available to metamorphosis of spermatids.

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1. Metachromasia was ma n ifested in the capsular and interterritorial matrix of tracheal cartilage, the goblet cells of trachea, duodenum, jejunum and colon, the interelastic sapaces of aorta, and the stroma of cornea, when these specimens fixed in 1% CPC-10% neutr al formalin were stained with a solution which was prepared by dissoloving 50 mg of hematein and 50 mg of aluminum ammonium sulfate in 50 ml of 0.1 M acetate buffer at pH 3.6.
2. On the basis of positive result s obtained by testicular hyaluronidase, Streptomyces hyaluronidase and neuraminidase digestions, it is suggested that the metachromatic substances are composed of chondroitin sulfate A and C which are present in the tracheal cartilage, sialic acid which is present in the goblet cells of trachea, duodenum and jejunum, the interelastic spaces of aorta, and the stroma of corn ea, and O-acylated sialic acid which is present in the colonic goblet cells.
3. In view of the results obtaining with methylation and sap o nification treatment in addition to enzymatic digestion, it is suggested that hematein-lake combines with the sulfate group of chondroitin sulfate A and C, and carboxyl group of sialic acid. In addition, since the metachromasia is inhibited by addition of MgC12, it is presumed that the combination is due to ionic bonding.

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1. Hematein shows a stron g affinity to elastic fibers at pH 6.0-8.0.
2. Affinity of hematein to elastic fibers can be augmented foll o wing addition of the mordants such as aluminum ammonium sulfate, ferric ammonium sulfate, phosphotungstic acid and ammonium molybdate.
3. Both hydrogen and ionic bonds in elastin partic i p ate in the staining of elastic fibers with hematein.

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