188 SUMMARY OF CURRENT RESEARCHES RELATING TO 



shaking them and warming them at the same time. By combining 

 these two methods there is induced a " nuclear lability," which renders 

 these eggs susceptible to the influence of carbon dioxide as a provocative 

 of cleavage. Stages with thirty-two blastomeres were produced. 



Influence of Carbon Dioxide on Ova of Echinoderms.*— C. Viguier 

 finds that this influence does not uniformly act, as Delage has asserted, 

 as a temporary poison. Like some other re-agents, it has a variable 

 influence ; it is sometimes favourable and sometimes injurious ; it acts 

 differently on nearly related types and even on eggs of the same species, 

 according to their condition at the time. 



New Genus of Diadematidse.f — Th. Mortensen describes Lisso- 

 diadema lorioli g. et sp. n. — a small Bchinoid from the Bay of Amboina 

 which was previously regarded by de Loriol as a young specimen of 

 Asthenosoma varium. Re-examination shows that the form is an in- 

 teresting new type of the family Diadematidge, with a near relative in 

 Echinotlirix. 



Habits and Life-History of Stichopus japonicus.J— K. Mitsukuri 

 notes that the breeding season of this holothurian ends with the latter 

 half of July. Then the individuals crawl out into dark places under 

 rocks and cease to take food, passing into an inactive state which may be 

 called " summer sleep." The alimentary canal becomes reduced to a 

 slender, almost thread-like tube. In autumn the animals crawl out 

 again, and begin to feed. The branches of the dendritic gonads elongate 

 quickly, and are ripe about the middle of May ; the height of the re- 

 productive season lasting till the middle of July. 



Mitsukuri thinks that the genital tubes ought to be regarded simply 

 as local lateral growths of the strictly germinal area/ which is lodged in 

 the median line of the dorsal mesentery. A certain number of tubes are 

 produced as each year's crop. Some of the next year's crop may be seen 

 as delicate and slender tubes in front of the enlarged and fully-grown 

 tubes of a given year. After the genital products are shed, the tubes 

 seem to be gradually absorbed. 



It seems that Stichopus japonicus reaches the adult condition in two 

 whole years ; and that after reaching this it goes through a regular 

 spawning season only at the end of another year, i.e. the third year from 

 the beginning. Some probably live for five years. Some hints as to 

 protecting, propagating and increasing these holothurians are given, e.g. 

 by providing piles or dykes of loose stones for the summer retreat, and 

 for the shelter of the larva?. After making this suggestion, the author 

 found that the plan had been tried in the somewhat out-of-the-way island 

 of Oki for a hundred years or more. 



Variation in Ophiocoma nigra.§ — D. C. Mcintosh has studied in 

 this brittle star the most general shape of the disc, the shape and size of 

 the coloured patch (if any) on the disc, the correlation between arm- 

 length and disc-breadth, the percentage of specimens with an abnormal 



* Comptes Rendus, cxxxvi. (1003) pp. 1687-90. 



t Revue Suisse Zool., xi. (1903) pp. 393-8 (4 figs.). 



j Annot. Zool. Japon., v. (1903) pp. 1-21 (4 figs, and tables). 



§ Bionutrika, ii. (1903) part 4, pp. 463-73 (8 figs, and 5 tables). 



