ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 553 



by an examination of the gonads. It is suggested that the subsequent 

 dimorphism is determined by the etiological differences. The sedentary 

 habits of the female induce a hypertrophy of the digestive functions, 

 impossible in the pelagic male. A minute description is given of the 

 suctorial apparatus. 



Spermatozoa of Decapoda.* — N. K. Koltzoff discusses in a very 

 exhaustive manner the spermatozoon in Decapods as an introduction to 

 a consideration of the problem of cell-form. There is a chapter on 

 comparative morphology, which includes an account of the development 

 of the various structures, nuclear and cytoplasmic, with a statement of 

 homologies with the usual sperm type ; a chapter on biophysics, in 

 which are discussed, inter alia, the dependence of the external form of 

 the Decapod sperm upon osmotic pressure, the origin of the form in 

 histogenesis, and its fixation ; a chapter on physiology, dealing with the 

 movements of the sperm appendages, the capsule explosion, and the 

 functions of the separate sperm " organs " ; and a concluding section, 

 treating of such matters as the significance of the central body and the 

 mitochondria, and the organisation of the cell. 



Annulata. 



Collateral Budding- in a Syllid.f — Akira Izuka describes in Try- 

 panosyllis misakiensis sp. n. the production of numerous collateral buds 

 .at the posterior end of the body. There were fourteen sexual zooids 

 attached to the ventral aspect of the posterior end. After full maturity 

 the buds will evidently separate from the asexual mother individual. 



Nephridia of Arenicola.J — R. S. Lillie gives a full account of the 

 structure, origin, and histological differentiation of the nephridia in 

 A. crista/ a Simpson. Particular attention is given to the relation of the 

 nephridia to the body segmentation and to the septa, and the mode of 

 development of nephrostome, glandular portion, and terminal vesicle. 

 There is also added a brief account of the anatomy and histology of the 

 adult nephridium. 



Heteronereis of Thames Estuary.§ — H. C. Sorby gives some in- 

 teresting notes regarding the Heteronereis of several species of Nereis. 

 He has spent several months in the year for more than twenty years on 

 the waters of the Thames estuary, and only on five occasions has he 

 seen large numbers of Heteronereis swimming at the surface. Some 

 account of these occurrences is given, and also other notes upon the 

 following species : — iV. diver sicolor, N. dumerilii, N. longissima, 

 N.pelagica, N. cultrifera. 



Nematohelminthes. 



Reducing-division in Ascaris.|| — R. F. Griggs presents evidence 

 which seems to him conclusive that the reduction-division in Ascaris is 



* Arch. Mikr. Anat., lxvii. (1906) heft 3, pp. 364-571 (3 pis. and 37 figs.). 

 t Arniot. Zool. Japon, v. (1906) pp. 283-7 (4 figs.). 



♦ Mitth. Zool. Station Neapel, xvii. (1905) pp. 341-405 (4 pis. and 1 fig.). 

 § Journ. Linn. Soc, xxix. (1906) pp. 434-9. 



|| Ohio Nat., vi. (1906) pp. 519-27 (1 pi.). 



Oct. 17th, 1906 2 



