ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 567 



Homing" of Limpets.* — G-. Bonn discusses the so-called local 

 memory of Patella, and gives the results of a large number of experi- 

 ments. He finds that the homing is not always certain. Gravity 

 seems to influence the movements. There are lines of least resistance 

 on the rocks which are followed, as one might follow them in a forest. 

 But it is not necessary to invoke a muscular or visual memory. 



Pallial Caecum in Bulloidea.f — Remy Perrier and Henri Fischer 

 have investigated the diverticulum of the pallial cavity in Actaeon and 

 Scaphander, which forms a long tube ending in a cul-de-sac, and coiling 

 within the shell, parallel to the visceral mass, yet without fusing with it. 

 This pallial cascum is found in all the Bulloidea. It contains two 

 ciliated bands. It may be free, e.g. in Aphistrum, or adherent, e.g. in 

 Acera, or in a devious spiral of its own, e.g. in Bulla. 



Pteropods and Heteropods of Coasts of Ireland.! — Anne L. Massy 

 reports on a collection of seventeen species, seven of which have not 

 hitherto been recorded from the British Islands. The collection includes 

 Glione gracilis sp. n., distinguishable from G. limacina Phipps by the 

 large head, narrow body, absence of coloration, and differences in the 

 spines of the hook-sac and teeth of the radula. The Heteropoda are 

 only represented by a few records of Carinaria lamarcTcii. 



Maturation and Fertilisation in Cymbulia peronii.§ — A. Nekrassoff 

 gives a detailed account of these phenomena in this Pteropod mollusc. 

 The following are some of his results. The cleavage centrosomes arise 

 apparently de novo, in any case not from the sperm-centrosome. The 

 cytoplasm of the ovum influences the head of the spermatozoon, which 

 changes its shape, shortening and rolling up. After the constriction of 

 the second polar body, the sperm-head is attracted by the centre of the 

 degenerating radiate system of the ovum. After the union of the sex- 

 nuclei the sperm-nucleus behaves like the half of the nucleus of ordinary 

 cells. It takes equal part with the ovum-nucleus in forming the achro- 

 matin figure of the karyokinesis, and provides half the number of chro- 

 mosomes for the first cleavage spindle. The tail of the spermatozoon is 

 gradually absorbed by the cytoplasm. 



8. Laniellibranchiata. 



Seasonal Variations in the Glycogen made by Oysters. [| — J. A. 

 Milroy finds that the percentage of glycogen varies to a large extent 

 with the weight or nutritive condition of the oysters. As regards seasonal 

 variations, there is a gradual rise in the percentage from the beginning 

 of August until the middle or end of October. This is succeeded by a 

 fall which reaches its minimum about the middle of December. From 

 that period onwards the percentage rises until it reaches its maximum 

 some time between the beginning of April and early in May. The per- 



* Comptes Rendus, cxlviii. (1909) pp. 868-70. t Tom. cit., p. 956-9. 



% Fisheries, Ireland, Sci. Invest., 1907, ii. (published 1909) pp. 1-52 (1 pi.). 

 § Archiv Mike. Anat., lsxiii. (1909) pp. 913-91 (5 pis. and 17 figs.). 

 i| Fisheries, Ireland, Sci. Invest., 1907, iv. (published 1909) pp. 3-12(7 diagrams) # 



2 Q 2 



