GERM CELLS IN NEMATODES, SAGITTA 181 



the periphery at the vegetative pole (Fig. 54, B, x). 

 This body, which he called the *'besondere Korper," 

 consists at first of " grobkornigeri " plasma which 

 stains like chromatin but not so intensely ; later it 

 condenses into a round homogeneous body with a 

 sharp contour. During the first five cleavage 

 divisions the "besondere Korper" is always confined 

 to a single cell. At the completion of this fifth 

 cleavage (32-cell stage), the blastomere containing 

 this cytoplasmic inclusion is recognizable as the first 

 *'Urgeschlechtszelle" (Fig. 54, C, G) and its larger 

 sister cell as the first **Urentodermzelle" (Fig. 54, 

 Cy E). The primordial germ cell is the last to divide 

 during the sixth cleavage and the "besondere Kor- 

 per" does not, as before, pass entire into one of the 

 daughter cells, but breaks up into a number of pieces, 

 part of which are included in each of the two daughter 

 cells (Fig. 54, D, X). One of these daughter cells 

 apparently acquires more of the *'besondere Korper" 

 than the other. This division appears to Elpatiew- 

 sky to be differential, separating the primordial 

 oogonium from the primordial spermatogonium, the 

 latter being the cell which receives the larger portion 

 of the "besondere Korper" and which during the 

 next (seventh) division is sHghtly delayed (Fig. 54, 

 F). Subsequent to the seventh cleavage the remains 

 of the "besondere Korper" become pale and grad- 

 ually disappear, apparently dissolving, and in the 

 four germ cells resulting from the next division only 

 occasionally can stained granules from this body be 

 distinguished. 



