IIO W. M. SMALLWOOD. 



subsequent development. Voigt believes that he can trace the 

 nebenkorpenchen from spermatogonium, through spermatocyte 

 and spermatid to the apex of the sperm, which I very much 

 doubt. What he has described and figured for the nebenkor- 

 penchen in some of these early stages, I have frequently found 

 in the free cells in the ccelome which are undoubtedly leucocytes. 

 Kukenthal ('85, p. 454) who has made a study of the lymphoid 

 cells of Annelids states that "The fluid of the ccelome is not 

 homogeneous, but contains a number of elements of various 

 kinds, among which the rather large rounded cells are the most 

 conspicuous ; these are the lymphoid cells, and of them there are 

 two kinds. Some have more or less finely granular protoplasm, 

 and others contain clear highly refractive granules, which are 

 colorless ; others are still larger, and of a yellowish-brown color." 

 Voigt states that the nebenkorperchen can only be seen in the 

 free living cells in some stages which is an additional confirma- 

 tion of my criticism. 



The statement that the spermatid has two nebenkorperchen, 

 one of which is derived from the thickened protoplasm of the 

 cell wall, is of course due to his inability to detect the origin of 

 this body in the spermatocyte centrosome. The manner in 

 which the nucleus is supposed to form the head of the sperm is 

 somewhat unique. The head of the sperm grows out of the 

 nucleus much as the radicle grows out of the bean, the nucleus 

 becoming smaller as the head lengthens instead of the complete 

 and simultaneous transformation of the whole nucleus into the 

 head. 



Branchiobdella instabilia is so closely related to Brancliiobdella 

 varians that the spermatogenesis of the two species is probably 

 very nearly identical and a restudy of the latter will probably 

 show its full agreement with the former as well as with other 

 annelids. 



SYRACUSE UNIVERSITY, DEPARTMENT OF ZOOLOGY, 

 April 15, 1906. 



LITERATURE CITED. 

 Bloomfield, J. E. 



'80 On the development of the spermatozoa. I. Lumbricus. Ouart. Jour. 

 Micr. Sc., XX. 



Calkins, G. N. 



'95 The spermatogenesis of Lumbricus. Journ. Morph., Vol. II. 



