470 J. DUESBERG 



the primordial germ-cells of Coregonus. Aunap found only 

 granules; in Fundulus, these cells contain filaments, most of 

 them in little heaps and in close relation to the nucleus. Sup- 

 posing that these cells are primordial germ-cells and that conse- 

 quently a comparison with Aunap's results is justified, such a dif- 

 ference may be explained in several ways: by admitting either 

 the existence of specific variations, or a change in the shape 

 of the chondriosomes with the evolution of the germ-cell, or, fi- 

 nally, the imperfect preservation, in Aunap's preparations, of 

 these deeply situated parts of the body of the embryo. It must, 

 however, be added immediately that the question of the shape 

 of the chondriosomes in the primordial germ-cells has completely 

 lost its importance, since Swift ('14) has demonstrated, con- 

 tradicting Tschaschin, that in birds these chondriosomes ''are 

 not at all characteristic; they resemble the mitochondria of the 

 somatic cells (p. 495)." 



Curiously enough, if my findings on these cells of Fundulus 

 agree with Felix's description of the primordial germ-cells of the 

 Salmonides, my own observations on Salmonides do not agree 

 with that description of Felix. In the rainbow trout, the pri- 

 mordial germ-cells, easily recognized as such in the genital 

 region, are conspicuous, not only because of the size of the cell 

 and of the nucleus, but also by the presence of peculiar globu- 

 lar inclusions. I found in these cells three kinds of bodies: 1) 

 fat-droplets, nearly always conglomerated in one large globule 

 and located at one pole of the nucleus; 2) granules scattered 

 throughout the whole cell; these stain lightly in red in acid 

 fuchsin-methylgreen preparations, in pink with Benda's stain; 

 3) very minute mitochondria (fig. 7b). The fat-globule is dis- 

 solved after fixation in Regaud and none of these three kinds of 

 bodies is preserved in Zenker; this explains perhaps why Felix 

 did not see them. In this case, my observations on chondrio- 

 somes agree with Aunap's, except in that the granules he figures 

 are larger. Whether the granular form corresponds actually 

 to the. form of the chondriosomes in the living cell is hard to 

 decide, for the genital region is not easily reached by the fixing 

 fluid. 



