188 SUMMARY OF CURRENT RESEARCHES RELATING TO 



in the cytoplasm of the basal parts. Iron is frequently found in the 

 cells of the lateral walls of the liver, and is always present after some 

 solution of ferrum oxydatum saccharatum Las been added to the sea- 

 water. 



Tunicata. 



Oogenesis in Tunicates.* — Mr. F. W. Bancroft has made an elabo- 

 rate series of observations on this subject, with special reference to a 

 Californian species of Distaplia, apparently nearly allied to D. rosea. 

 The development of the gonads conforms in general to the type first 

 described by Van Beneden and Julin, and the zooids are always herma- 

 phrodite, the organs being simultaneously functional. In regard to the 

 incubatory pouch, it would appear that this has a direct connection with 

 the oviduct, so that the ova can be passed into it without entering the 

 peribranchial sac. As to the vexed question of the origin and function 

 of the " test-cells " or kalymmocytes, the author finds no evidence for 

 the view tliat they have an intraovular origin, while there is every 

 reason to believe that they are migratory follicular cells, whose function 

 is to feed the ovum. He opposes the old view, recently supported by 

 Salensky, that they have anything to do with the formation of the test, 

 and in a postscript to the paper adheres to this position after having had 

 an opportunity of inspecting Salensky's sections. 



As in Distaplia magnilarva according to Davidoff, the whole of the 

 cytoplasm is converted into yolk-bodies, and the formation of yolk is 

 associated with a gradual shrinkage of the germinal vesicle. In his 

 interpretation of the changes in the vesicle the author differs markedly 

 from Davidoff, who, as he thinks, has confused nucleolus and germinal 

 vesicle. The process of maturation was not observed in detail. 



Maturation and Fertilisation in Ciona intestinalis-f — Herr St. 

 Golski notes the following points : — the germinal vesicle is very large 

 and contains a very large nucleolus ; the directive spindles are very 

 small ; the retraction of the spindle is subsequent to fertilisation ; the 

 directive spindles show distinct centrosomes, central spindle, and inter- 

 mediate body ; they are first tangential and then radial in position ; the 

 first polar body often divides into two ; the sperm-centrosome comes 

 from the middle portion and gives rise to the cleavage centrosomes ; 

 polyspermy sometimes occurs ; the occurrence of central spindles and 

 intermediate bodies was observed in the segmentation. 



INVERTEBRATA. 



Mollusca. 



Bionomics of Mollusca.^ — F. N. Balch publishes a list of marine 

 molluscs found in a somewhat isolated area (Coldspring Harbour, Long 

 Island), the interest of which is its general bearing on the conditions of 

 life of the littoral Mollusca. The physical conditions in the area are 

 uniform, and the bottom deposit everywhere morainic mud with a few 

 boulders and stones. Nevertheless, the mollusca are of distinctly varied 



* Bull. Mus. Conip. Zool. Harvard, xxxv. (1899) pp. 59-112 (6 pis.). 

 t Anz. Ak. Wiss. Krakau, 1899, pp. 124-30. See Zool. Centralbl., vi. (1899) 

 pp. 94o-6. \ Proe. Boston Soc. Nat. Hist., xxix. (1899) pp. 133-62 (1 pi.). 



