ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 327 



et sp. n. somewhat closely related to Lumbriculus spiralis of Leidy, and 

 Embolocephalus multisetosus sp. n. 



Nervous System of Annelids.* — Dr. J. Havet has employed Golgi's 

 method in the study of the minute structure of the nervous system in 

 C3rtain Oligochaetes and Hirudinea. He finds that in the latter the 

 skin contains numerous bipolar nerve-cells, usually arranged in groups, 

 and having protoplasmic prolongations which converge to form a kind 

 of nerve-plate. In Oligochsetes these external prolongations are absent. 

 In both, sensory nerves are formed by internal prolongations of these 

 nerve-cells, and these sensory nerves ultimately pass into the ganglia of 

 the ventral nerve-chain. The ganglia have a peripheral coat consisting 

 of several layers of unipolar (Hirudinea and Oligochaetes), or bipolar 

 (Oligochsetes), or multipolar (Oligoclnetes) nerve-cells, which are usually 

 pear-shaped, and vary greatly in size. The chief prolongations assist 

 to form a lateral nerve of the same side as that in which the cells lie 

 to which they belong, and they also assist to form a lateral nerve of the 

 opposite side. Most of the important prolongations give off secondary 

 branches, which ramify and intertwine to constitute the dotted substance 

 of Leydig. These secondary branches bear pear-shaped appendices, and 

 end in thickened points. All the nerves are formed by the prolonga- 

 tions of the sensory or motor nerve-cells, and the two kinds of prolonga- 

 tion can be distinguished by their minute characters. 



Copulation in Leeches.f — Emile Brumpt reviews the literature of 

 this subject, and gives an account of his own observations in the dif- 

 ferent groups of Hirudinea, with special reference to the phenomenon 

 of "hypodermic impregnation." In Hirudo troctina he was able to 

 observe clearly that one individual acted as a male and the other as a 

 female ; the observation was made on two separate occasions, and in 

 both cases the larger individual acted as the male. Similar observations 

 have been made by Etrard for other Gnathobdellidee. In the genus 

 Herpobdella the author confirms Isao Ijima's observation that the - 

 spermatophores are deposited on the integument of the body, and be- 

 lieves, contrary to the opinion of that author, that this is the normal 

 method of fertilisation. In Callobdella among Khynchobdellidse fer- 

 tilisation is reciprocal, a spermatophore being found in or near the 

 female orifice of each individual at the end of copulation. In Ponto- 

 bdella the author observed the reciprocal deposition of a spermatophore 

 on the surface of each of the copulating individuals ; the contents sub- 

 sequently pass through the skin, which exhibits a permanent mark at 

 the spot. In Piscicola the spermatophore is placed in the female orifice, 

 and fertilisation appears to be unilateraL In the case of the Glosso- 

 siphonidse the author has been able to confirm and amplify the state- 

 ments of previous authors as to the occurrence of the " hypodermic 

 impregnation " of Whitman ; but on the other band, like Kowalevsky, 

 he has been unable to obtain experimental verification of the view that 

 this impregnation results in effective fertilisation. His observations on 

 the subject are as yet incomplete, and the present paper has for its 

 special object the emphasising of the important blanks in our know- 



* La Cellule, xvii. (1900) pp. 65-136 (7 pis.). 



t Bull. Soc. Zool. France, xxiv. (1899) pp. 221-38. 



