ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 29 



Indian Ocean Dredging.* — Dr. A. F. McArdle reports ou the dredg- 

 ing season 1899-1900, and notes some of the most interesting finds : — 

 e.g. a very largo (12 in.) adnlt male of Bathynomus giganteus, the 

 strange crab Trichopeltarium ovale, the Atlantic fish Hoplostethus atlanti- 

 cum, 28 specimens of Glyplwcrangon investigatoris, Bleurotoma symbiotes 

 encrusted with Epizoantlms. 



Mollusca. 

 a. Cephalopoda. 



Effect of Reagents on Segmenting Eggs.f — Wl. Schimkewitsch 

 has made a series of experiments as to the effect of concentrated sea- 

 water, sulphate of manganese, sodium bromide, potassium iodide, and 

 other substances, on the meroblastic eggs of Loligo vulgaris. He finds 

 that the effect of any solution is twofold, the mechanical effect due to 

 changes of pressure being distinct from the chemical effect. It would 

 appear that of the two the former has the greater influence, as is seen 

 from the fact that two compounds very different chemically may produce 

 the same effect on the ovum. The most obvious effect produced is usually 

 the formation of outgrowths of the egg or furrows on its surface, which 

 produce notable changes in the growth and relations of the germinal 

 layers. At certain stages in the development the ectoderm, under the 

 influence of certain reagents, exhibits a teloblastic mode of increase, 

 comparable to that seen, e.g. in primitive mesoderm cells, which suggests 

 that the teloblastic method, when it occurs normally, may be due to 

 special conditions of pressure. Again, certain reagents result in the 

 shell-gland arising by a process of delamination instead of the normal 

 invagination process. But while the author in this way points to various 

 artificially produced phenomena which cast light upon normal processes, 

 it would seem that the complete interpretation of the new conditions is 

 not as yet possible. 



Plague of Octopus.J — Mr. W. Garstaug reports that until the spring 

 of 1899 the true or common Octopus (0. vulgaris) was comparatively 

 rare in the neighbourhood of Plymouth, since the opening of the Ply- 

 mouth Laboratory in 1888. But in 1899 and 1900 the numbers have 

 enormously increased, on both shores of the English Channel — probably 

 in association with the warmth of recent summers — and the result has 

 been serious loss to crab and lobster fisheries. Mr. Garstang suggests 

 the advisability of temporarily suspending all fishing for crabs and 

 lobsters, and of employing a number of men to fish for octopus, e.g. with 

 unbaited pots. 



y. Gastropoda. 



Locomotion of Fulgur.§ — Mr. W. S. Wallace observed the manner 

 and rate of locomotion in Fulgur carica up the glass side of an aqua- 

 rium. He says that the progression of the foot-surface over the 

 smooth glass is accorujdished by two devices: — (1) the pedal secretion 

 is adhesive ; and (2) the foot, when not in motion, becomes a vacuum- 

 cup of considerable efficiency. But these cannot account for progression, 



* Ann. Nat. Hist., vi. (1900) pp. 471-8. 



t Zeitscbr. wiss. Zool., lxvii. (1900) pp. 491-528 (4 pis.). 



% Journ. Mar. Biol. Ass., vi. (1900) pp. 260-73. 



§ English Mechanic, lxxii. (1900) p. 244 (4 figs.).] 



