[in Japanese]

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[in Japanese]

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[in Japanese]

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It is studied that all of S contained in gelose is combined as sulphuric acid and there-lation between the amount of SO₃ and jellyfying power is discussed.

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In order to determine the spawning period of Cucumaria japonica S_EMPER we examined the gonads of the samples, which were obtained from Muroran between November, 1939 and November, 1940.
In this species the gonadial tubes are found clearly all the year round and do not much wither even in the non-spawning period. The tubes are found more or less to contain ripe sexual cells nearly all the year round. Both sperm and egg are relatively large, viz., the length of the ripe egg is 540μ. and its breadth, 474μ, and the sperm has a whole length of about 67μ.
Spawning of this species extends over a considerably long period, from early March to middle November, with a maximum from early or middle July to late September. During the maximum spawing period proliferation of sexual cells are very active as well as extrusion of ripe ones.

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As far as we are aware, none ever described in detail the life-history of fish belonging to Scleroderm in Japan, while the, present fish, one of Scleroderm, is a common commercial as well as game fish in Ise and Mikawa Bay. The present study is summerized as follows :
(1) The breeding season covers the duration from June to August. The number of eggs the female possesses is counted by examination of the ripe gonad. The result is shown in Table 1.
(2) The egg is pelagic. Artificial fertilization is by no means difficult and gives success-ful result. The larvae and the youngs are described and figured (Text-figures).
(3) The yearling grows up to ca. 10 cm in body-lenght at the fall of the year. From that it is clear that the small size group (9-14 cm) observable in the breeding season belongs to the 2nd year class. The age-determination is also made by the study of the vertebral bones. The growth rate is shown in Table 5.
(4) The male ripens in smaller size than the female. The biological minimum is 12cm in the male, while it is 15cm in the female, and the former belongs to 2nd year class and the latter to 3rd year class.

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The life-history of Tinocladia crassa (OKAM.) KYLIN was studied. In Ise- and Mikawa- bay, the alga is found from February till the end of June, and it has only unilocular sporangia in April, May and June. After liberating swarm•spores (zoospores) from the unilocular sporangia, it begins to decay and then disappears. Thereafter no macroscopic plant-body is seen in nature till the next spring, when the young plantlets appear.
In the laboratory, swarm-spores (zoospores) from the unilocular sporangia develop in direct germination without conjugation and make the microscopic protonemal germlings (stre-blonemoid devolopment). When the environmental condition is good, they grow well, but when the weather becomes warmer, some cells of this protonema (germling) are covered with a thick membrane, and their contents become granular. During the summer-time, they cease their further growth and rest in this stage till the better condition comes in, when a slender minute protonemal gametophyte sprouts out from each of these resting cells. In maturity, the game-tophyte bears many multilocular sporangia, and in each of the sporangia 4-6 gametes are finally made. After escaping from the sporangium gametes swim about and they are able to conjugate. Yet, most of them not having conjugated can germinate apogamously. On the other hand, the zygote germinates directly and grows in an Anlage of the Tinocladia plant, i. e., the sporophyte. The apogamously germinated gamete develops into a slender microscopical germling which, afterwards, bears again multilocular sporangia in spite of unilocular sporangia. These results were observed by the culture experiments for about an year (from 1940, April till 1941, April).
After these observations, it seems to be reasonable that, in nature, the Tinocladia plant aestivates in the stage of the thick-walled resting cells.

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