204 KINGSBURY. [Vol. II. 



garis) ; so that the way was well paved for the recognition of 

 similar results in Salamandra as well. 



MeveSji finally, after a careful reinvestigation of the sper- 

 matogenesis of Salamandra, has found that Flemming was 

 right as to the number of cell generations, and vom Rath 

 wrong ; that there is no tetrad formation and no reduction in 

 the Weismannian sense ; both of the final divisions being equa- 

 tion divisions; the first heterotypic in character, the second 

 homotypic — not mixed, as Flemming had thought. 



The large number of forms in which tetrad formation or its 

 equivalent has since been found to occur might suggest that 

 vom Rath is nevertheless right, or partially right, and Meves 

 wrong. My results, however, upon the American salamander 

 DesmognatJuis fusca confirm Meves's interpretations in all the 

 essential points ; no tetrad formation occurs, unless exception- 

 ally, and the two final divisions recognized by Flemming are 

 both equation divisions. Though this is the case, there yet 

 exists the possibility of a qualitative reduction, as will be indi- 

 cated below. 



After the last division of the spermatogonia there occurs a 

 well-marked synapsis stage, such as has been recognized by 

 Moore 2 in Elasmobranchs, in which the detailed structure of 

 the nucleus becomes very difficult to make out. The chroma- 

 tin emerges from the synapsis in the form of a fine, intricately 

 coiled thread or threads (it. has not yet been 

 ascertained which), and the nucleus enters on 

 its period of growth preparatory to the first of 

 the two "reducing" divisions. During this 

 period the chromatin thread (or threads) shortens 

 and thickens, and finally may be resolved into 

 • ^^^' '■ twelve horseshoe-shaped loops, which, in most 



cases at least, are so arranged as to have their ends — the open 

 side of the loop — opposite the centrosphere, with its centro- 

 some, now precociously divided (Fig. i). 



The division into which the nucleus is about to enter pro- 



1 Meves, Fr., " Ueber die Entwickliing der niiinnlichen Geschlechtszellen bei 

 Salamandra maculosa," Arch./, tnikr. Anat. Vol. xlviii, pp. 1-S3. 1896. 

 ^ Quart. Journ. Micr. Sci. Vol. xxxviii, pp. 275. 1895-96. 



