710 SUMMARY OF CURRENT RESEARCHES RELATING TO 



buds — analogous to Btatoblasts in Bryozoa and gemmules in Sponges — 



in this Aseidian. He discusses the difficult fact that the bud arises from 

 ectoderm and mesenchyme, and yet forms an entire animal. The 

 conception of homology breaks down in the case of buds ; organs may 

 be isomorphic and analogous, and yet not homologous, being hetero- 

 genetic. 



INVERTEBRATA. 



Mollusca. 

 7. Gastropoda. 



Defensive Pallial Glands in Scaphander.* — Ilemy Perrier and 

 Henri Fischer find that Scaphander lignarius shows a high degree of 

 differentiation as regards pallial glands. When the animal is irritated 

 it emits a yellowish viscous fluid which appears to be defensive. The 

 secretion is produced by glands in the mantle. There are two kinds, 

 (1) the glands of Blochmann (described in Aplysia, etc.) along a zone 

 on the under surface of the mantle parallel to its margin ; and (2) the 

 intra-pallial glands immediately in front of the anterior lip of the 

 pallial aperture. 



Sense of Taste in Fresh-water Snails.f — Henri Pieron has experi- 

 mented with Linuuea auricularis and L. stagnates, and finds that the 

 sense of taste, of " alimentary discrimination," as he calls it, is localised 

 in the most anterior part of the foot. The same region shows sensi- 

 tiveness to strong odours, but this olfactory sensitiveness is demonstrable 

 over a wider area than the gustatory sensitiveness. It is found on the 

 margins of the foot to the posterior end, on the head, and at the 

 osphradium. 



Feeding Habit of Fulgur and Sycotypus. J — H. S. Colton has 

 studied the behaviour of these Gastropods, which live well in captivity. 

 Fulgar probably attacks any Lamellibranchs ; Sycotypus will attack any 

 except Venus. Oysters are eaten in less than one hour, clams in 1 h hour, 

 ijuahogs (Venus mercenaria) in from seven hours to three days. The 

 animals do not bore the shells with the radula. They open shells of 

 oysters by wedging their own shell between the valves, and tear out the 

 flesh with the radula. Some shells are partly broken in this way. 



The meals of Fulgur and Sycotypus are few and far between. The 

 time between meals is spent buried in the sand. Xo clear evidence of 

 intelligence was discovered. 



Arthropoda. 

 a. Insecta. 



House-fly.§ — C. (1. Hewitt publishes the second of three papers on the 

 house-fly (Musca domestica). The present paper deals with the breeding- 

 habits and with the structure of the larva. Horse-manure is preferred 

 by the female as a nidus for the eggs, but all sorts of excrementitious 

 matter, as well as rotting cloth, decaying vegetables, and the like, may 



* Comptes Rendus, cxlvi. (1908) pp. 1163-6. 



t Op. cit., cxlvii. (1908) pp. 279-80. 



% Proc. Nat. Sci. Philadelphia, 1908, pp. 3-10 (5 pis. and 1 fig.). 



§ Quart. Journ. Micr. Sci., liv. (1908) pp. 495-545 (4 pis.). 



