418 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Structure of Leda.* * * § — Herr W. Stempell describes the structure of 
Leda sulculata Gould, — especially the peculiar dorsal mantle-processes; 
the imperfect intersiphonal septum which, indeed, is only hinted at ; 
the tendency to coalescence of the Protobranch gills; the absence of 
any hypobranchial gland ; the distinctly defined oesophageal cavity ; 
the absence of any hint of a jaw-like structure ; a narrow duct between 
the pericardial portion of the kidney-tube and the terminal part of the 
ureter ; and the direct opening of the genital organs into a cloaca. Thus 
the author shows that there are many divergences between his observa- 
tions and those of Pelseneer on Leda pella L. ; and it seems necessary to 
modify Pelseneer’s statement of the general characters of the Nuculidae. 
Phagocytosis* in *Development4 — Dr. C. De Bruyne finds that in 
Naiad se all the epithelial cells of the ovarian follicles contribute, in dif- 
ferent degrees, to the building-up of the ova ; the successful ovum lives 
at the expense of the adjacent elements of the follicle. 
The emergence of phagocytes and leucocytes from mucous surfaces in 
Anodonta is exaggerated in the incubatory cavity. There is a struggle 
for existence — in modified form — between the embryo and the maternal 
leucocytes. 
The embryonic cells are nourished by active exploitation of the 
phagocytes and leucocytes, and also by diffusion of material supplied by 
the histolysis of the phagocytes and leucocytes. This continues during 
the sojourn of the embryos within the gill-cavity of the mother. But 
similar processes of struggle and nutrition occur in the skin of the fish 
within which the larvae are temporarily parasitic. The same phenomena, 
mutatis mutandis , are to be seen in other types. 
Bryozoa. 
Development of Tubulipora.| — Mr. S. F. Harmer shows that a pro- 
cess of embryonic fission occurs normally in Tubulipora , as has already 
Veen demonstrated in Crisia and LicJienopora. His paper also contains 
*n account of the structure of the colony and of the ovicell, a history of 
the species and genus, with diagnosis of accepted forms (including. 
T. aperta sp. n.), a discussion of certain (excretory ?) vesicles found in 
the tentacles and other parts. Then follows a detailed description of 
the different stages in development, and there is a final chapter on the 
morphology of the internal parts of the ovicell. 
Arthropoda. 
Cleavage of the Cuticle in Moulting.§ — P. Pantel distinguishes an 
external dead zone of cuticle from an internal transition area between 
chitinous and protoplasmic structure. Between these a cleavage occurs 
in ecdysis or moulting, which the author has studied in Thrixion in 
particular. He describes the slow formation of the replacing cuticle, 
and the rapid hydraulic process by which the pressure of the liquid 
secreted by the hypodermis effects detachment of the old husk. Then 
* SB. Ges. Nat. Freunde BerliD, 1897, pp. 17-23. 
f Arch. Biol., xv. (1898) pp. 181-300 (5 pis.), 
t Quart. Journ. Micr. Sci., xli. (1898) pp. 73-157 (3 pls.).^ 
§ Comptes Rendus, cxxvi. (1898) pp. 850-3. 
