Methylthiouracil (M. T. U.) was administered to rats for a prolonged period, and hypothalamic neurosecretion (by CH-P method), PBI, 131I uptake and histological picture and paperchromatographic finding of the thyroid gland were investigated.
The remarkable goiter development, the productive change of the thyroid gland, decrease of the thyroid hormone both in the tissue and circulating blood on one side, and the increasing production of the neurosecretory material i a the cells and the increasing release of the material into the nerve fibers arising from the cells in the supraoptic and paraventricular nuclei on the other side, were apparently intiately related each other. In the histological observations, the secretory activity of the paraventricular nucleus was always accelerated than that of supraoptic nucleus.

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The neurosecretory phenomena in the paraventricular and supraoptic nuclei demonstrated by Gomori's CH and phloxine method was studied in relation to the change of thyroid function at the end of 2, 4, 6, 12 and 24hrs.after the injection of TSH.
1) In the cells of supraoptic nucleus, Nissl substance temporarily increased in the early period after the injection of TSH, then rapidly declined to the control level.
2) The production of the neurosecretory material in the cells and the release of the material from the cells into the nerve fibers arising from the cells in paraventricular nucleus were gradually increasing in the later period after the injection. On the other hand, the synthesis of thyroxin in the thyroid was accelerated in the early period and thereafter the release from the gland into the blood stream was accelerated. It seems that the neurosecretory material in the anterior hypothalamus, especially in the paraventricular nucleus, has something to do with the facts that the effect of the exogenous thyrotrophin reaches the maximum after it had been excreted or broken down.

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1. The melanophores of the marine isopod, Idotea japonica show a diurnal rhythm: they expand in the daytime, and concentrate by night. The diurnal rhythm is persistent under conditions of constant darkness but is interfered with under illumination, especially on white background.
2. When the animals are placed on white background, the melanophores begin to concentrate immediately, while the melanophores expand very slowly when the animals are placed on black background.
3. Injection of an extract of whole head of this animal caused melanophoreexpansion. Extracts of various nerve tissues were also injected in order to find the site of production of melanophore-expanding hormone. The order of the melanophorotropic activity is as follows: ASG>OSG=brain=OSG+brain>circumesophageal connective=ventral nerve cord=0. In this animal a melanophoreexpanding factor only is found and no melanophore-concentrating one.

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1) Salivary glands of rats decreased in weight markedly with the administration of thiourea or potassium thiocyanate in drinking water for two weeks and this change was recovered with the intraperitoneal injection of adequate dose of L-thyroxine.
2) The effect of chronically partial sialoadenectomy on iodine metabolism of rat thyroid was studied, and no significant change was observed in 40 and 60days after operation.

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In order to clarify whether the administration of oxytocin after weaning could prevent a decline in the metabolic activities of the mammary glands of rats, the following experiments were carried out.
The measurement of the respiration (R. Q. & -Qo2) and the production of lactic acid was employed to evaluate the metabolic activities of the mammary glands, and the morphological changes were also observed in the histological preparations to check the degree of involution.
The involution of the mammary glands after weaning was retarded by the administration of oxytocin to the mother rat during the experimental period. This finding was consistent with that of Benson and Folley (1957a, b).
However, the administration of oxytocin failed to prevent a steep decrease in the R. Q. and an increase in Q (lactic acid) which followed weaning. Although the lobule-alveolar system was maintained rather well in the mammary glands of rats receiving prolactin, a decrease in the R. Q. was also observed.

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Seven lactating rats, bearing lesions in the periventricular area of the medial hypothalamus that failed to rear their young, were subjected to oxytocin replacement twice daily. The litters of these rats received from 1-13g of milk daily during the experimental period (3-12 days). The lesions of these rats replaced with oxytocin were found in an area similar to that of the rats which failed to rear their young as reported in the previous paper, i. e. the periventricular area of the medial and caudal parts of the hypothalamus, and the area of the dorsoand ventro-medial nuclei.
The mating response was tested in 7 lesioned rats which failed to rear their young in the lst lactation. They delivered 1-9 young, 22-27 days after mating. Although the mammary gland was filled with milk which could be easily squeezed from their teats, 5 out of the 7 rats failed in rearing their young in the 2nd lactation. Oxytocin was given to these rats twice daily and a considerable amount of milk (0. 5-7. 4g/day) was received by the litter. The loci of the lesions were similar to those in the rats described above.
The study of the prolactin content of the anterior pituitary seems to illustrate that the suckling stimulus and the injection of oxytocin proved effective in lowering the prolactin contents of the pituitary in these rats, without reference of the presence of the hypothalamic lesions.
These results again imply the possibility of a selective impairment in the part of the hypothalamus, which is linked to the secretion of oxytocin, and the possibility that the role played by oxytocin in the release of prolactin, which is suggested by Benson and Folley (1957).

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Saliva-parotin-A could not be purified by fractional precipitation with trichloroacetic acid or ammonium sulfate nor by absorption with oxycellulose. In every case, the yield and the biological activities were distributed among various fractions.
By means of fractionation with ethanol in neutral solution, the effective substance was precipitated below 60% of ethanol concentration. The effective substance was concentrated to the bottom of tubes after ultracentrifugation for 5 hrs. at 54, 000 r. p.m.
Saliva-parotin-A was purified by successive applications of fractionation with ethanol and ultracentrifugation.

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Purified Saliva-parotin-A, almost homogeneous electrophoretically and ultracentrifugally, consisted of 18 kinds of amino acids. Its biological activities were extremely powerful and the minimum effective dose for rabbit serum calcium decreasing activity was 5-10μg, for circulating leucocytes activity 0.25-0.5μg and for calcification of rabbit incisor dentine 2μg.
The biological activities were extremely stable in acid and neutral solutions but comparatively unstable in alkaline solution.
It was partly digested by proteolytic enzymes without loss of its biological activities. It was inactivated by formaldehyde but not by nitrous acid, iodine, thioglycollic acid or cysteine.
It was not denatured by urea nor by guanidine.
Amino, tyrosine-phenyl and sulfhydryl groups in Saliva-parotin-A molecule were not responsible for revealing its biological activities.

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