ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 305 



worm's epithelium are (1) sensory nerve-cells, which are either arranged 

 in "organs" or occur singly; (2) here and there unipolar nerve-cells; 

 and (S) the diffusely distributed superficial nerve-endings which spread 

 out on the surface of the epithelium and form much ramified anasto- 

 moses and enter into relations with the epithelial cells (directly uniting 

 with sensory nerve-cells or ending freely at glandular cells). In the 

 buccal cavity there are other free nerve-endings — the club-fibres. 



At the basis of the epithelium there is the sub-epitlielial network, 

 consisting partly of processes of the sensory nerve-cells and partly of the 

 nerve-fibres of the superficial nerve-endings. In the buccal cavity there 

 are some bipolar nerve-cells in this network. The pharyngeal ganglion 

 is a dense aggregate of ganglion cells in the network. An important 

 point is the conclusion that the free nerve-endings do not enter into 

 connection with the processes of the sensory nerve-cells, but are quite 

 distinct from these and just as primary. 



Antarctic Polychsets.* — Ch. Gravier makes a preliminary note on 

 Antarctic Polychtets collected by the Charcot expedition. Thirty-sis 

 species, representing thirty-two genera, were obtained, and of these fifteen 

 species and one genus were new. The new genus — Helicosiphon — is a 

 Serpulid. Some of the species are closely related to boreal species. 

 There is a resemblance between the Antarctic Polychset fauna and that 

 of the extreme south of South America, 



Nematohelmintlies . 



Conditions of Development of Nematodes.t — L. Jammes and 

 A. Martin have made experiments on the beliaviour of the ova of 

 Ascaris vitulorum Goeze in different kinds of environment. The Qgg is 

 in most cases effectively preserved by the semi-permeability of the shell. 

 The nutrition of the embryo is secured by the reserves, and sufficient 

 water is allowed to enter. Temperature affects the rate of segmentation. 

 The host affords a succession of media, one acid, the other alkaline, and 

 a high and constant temperature. The embryo, protected by the shell, 

 traverses the acid medium of the stomach. Thereafter, when the 

 shell has become more permeable, the embryo passes into the alkaline 

 medium of the intestine, where it finds the conditions necessary for its 

 further development. 



Worm Parasites of the Russian Polar Expedition. f — 0. von 



Linstow records from the collections of this expedition (1900-3), two 

 Nematodes, Ascaris dehiscens sp. n., and A. osculata Rud. ; three Acan- 

 thocephala, two of which are new ; and seventeen Cestodes, most of 

 which are new. Amongst the Cestodes are representatives of two new 

 genera ; SkoriJcotvia g. n. is without vagina, but does not belong to the 

 sub-family Acoleinge ; it appears to belong to the Hijmpnolepis group. 

 Notohothrium g. u. belongs to the Bothriocephalidge. The type species 

 is N. arcticum sp. n., from Harelda glacialis. 



* Comptes Rendus, cxliv. (1907) pp. 43-4. 

 t C.R. Soc. Biol. Paris, Ixii. (1907) pp. 137-9. 



X M6m. Acad. Imp. Sci. de St. Petersbourg, sviii., p. 17 (3 pis.). See also 

 Centralbl. Bakt. Parasiteuk. Ref., xxxviii. (1906) p 771. 



