296 PROCEEDINGS OF THE ACADEMY OF [April, 



and Toyama (1903) ; the later, those of Munson (1907), Stevens (1906), 

 and Dederer (1907). The earlier workers concerned themselves 

 principally with the origin of the sex cells and the formation of the 

 spermatozoa, with especial reference to achromatic structures. Thus 

 Cholodkovsky finds in the closed flask-shaped end of the testis tube of 

 Laphria a large cell from which the cells of the testis arise ; and the same 

 subject has been studied by Yerson, La Valette St. George and Toyama 

 for Bombyx mori. Of all the earlier workers it is perhaps to La Valette 

 St. George, more than to any student of this group, that we are most 

 indebted, for to him we owe our present nomenclature. In 1884 Carnoy, 

 studying the larval testes of two moths, Chelonia caja and Arctia jul- 

 iginosa, made the observation, confirmed for the species here studied, 

 that all the celLs in the same cyst are in the same stage of development 

 and he figures and describes a few steps in the development of the first 

 spermatocytic division. In C. caja the twenty-four rodlike chromo- 

 somes divide longitudinally and move to opposite poles, while in A. 

 fuliginosa the chromosomes in a side view are seen upon a spindle as 

 dumb-bells with a transverse constriction. An equatorial plate shows 

 twenty-eight chromosomes so arranged that the twenty peripheral 

 chromosomes surround the eight interior ones. Carnoy's observations 

 on this group are very limited, owing to the fact that he found 

 his material unsatisfactory for studying the reconstructive stages 

 of the nucleus. Platnerwas the first to describe the whole course 

 of development of spermatogenesis for Lepidoptera. He described 

 the thirty chromosomes in the first spermatocytic division of 

 Pygcera and Sphinx as short rods with transverse constrictions, 

 and since the rods in the mitotic figure are arranged parallel to 

 the spindle axis, this constriction marks the first plane of division. 

 He confused the acrosome and centrosome, yet confirmed Butschli's 

 observations by showing that the " large mitosome, " Butschli's " Neben- 

 kern ", functions in the formation of the tail of the spermatid. His work, 

 like that of Erlanger (1896) and LaValette St. George (1897), deals 

 largely with the achromatic structures of the nucleus. Of special inter- 

 est in the light of recent work is Platner's account of the nucleolus, 

 which he describes as one or two rather large and deeply stain bag 

 bodies which are spherical in shape and eccentrically placed. It seems 

 very probable that these are comparable to the equal pair of idiochro- 

 mosomes figured for the forms described in the present study. 



Toyama (1902; his second paper, 1903, I have been unable to find) 

 describes the whole spermatogenic cycle for Bombyx. He begins with 

 a discussion of the formation of the early spermatogonia in the per- 



