THE REDUCING DIVISIONS IN THE SPERMATO- 

 GENESIS OF DESMOGNATHUS FUSCA. 



B. F. KINGSBURY. 



Despite the fact — perhaps rather because of it — that the 

 spermatogenesis of salamanders was the first to receive a care- 

 ful investigation, and has since been twice made the subject of 

 rather monographic treatment, there exist at present consider- 

 able confusion and disagreement in the results of the different 

 investigators. 



Flemming,! ji-^ jgS;, in his paper in which he recognized two 

 divergent types of mitosis to which he attached considerable 

 significance, the "heterotypic" and " homotypic," gave the 

 following scheme of spermatogenesis in Salaviandra : (i) a 

 period of multiplication of the cells ; (2) a period of growth in 

 which are formed the spermatocytes (of the first generation), 

 large cells ; these, by a division proceeding generally, though not 

 universally, according to the heterotypic plan, form daughter- 

 cells of medium size ; and these, by another division, generally 

 homotypic, sometimes heterotypic, form small (granddaughter) 

 cells which are directly transformed into the spermatozoa. 



Vom Rath,2 in 1893, followed with a paper upon the sperma- 

 togenesis of Salaviandra, in which he added to the three gen- 

 erations of cells recognized by Flemming three others, in the 

 last two of which occurred a reduction by means of tetrad 

 formation, which, after the appearance of Flemming's work on 

 Salamandra, had been already observed in several invertebrates, 

 and by vom Rath^ himself in the mole-cricket {Gryllotalpa vul- 



1 Flemming, W., " Neue Beitrage zur Kenntniss der Zelle. I. Die Kernthei- 

 lung bei den Spermatocyten von Salamandra maculosa," Arch. f. mikr. Anat. 



Vol. xxix, p. 389. 1887. 



2 Vom Rath, O., " Beitrage zur Kenntniss der Spermatogenese von Salamandra 

 maculosa," Zeitschr.f. wiss. Zool. Vol. Ivii. 1893. 



3 Vom Rath, O., " Zur Kenntniss der Spermatogenese von Gryllotalpa vul- 

 garis," Arch.f. mikr. Anat. Vol. xl, pp. 102-132. 1892. 



