102 GERM-CELL CYCLE IN ANIMALS 



and the tissues at and dorsal to the root of the 

 intestine" (Allen, 1911, p. 32). 



Of the more recent investigations, facts discov- 

 ered by Dodds (1910), Rubaschkin (1910, 1912), 

 Tschaschkin (1910), von Berenberg-Gossler (1912), 

 and Swift (1914) are especially worthy of mention. 

 Dodds (1910) found that in the teleost, Lophius, 

 the germ cells in the embryos cannot be definitely 

 distinguished previous to the appearance in their 

 cytoplasm of a body which stains like a plasmosome 

 (Fig. 31, A). Germ cells are undoubtedly segregated 

 before this period, but they exhibited no characteris- 

 tics with the methods employed which rendered them 

 distinguishable. Dodds believes that this cyto- 

 plasmic body is extruded plasmosome material, 

 probably part of one of the two plasmosomes pos- 

 sessed by many of the cells at this period. 



Rubaschkin, in 1910, announced the results ob- 

 tained with the eggs of the guinea-pig by certain 

 methods designed to bring into view the chondrio- 

 somes. He shows that the chondriosomes of the 

 undifferentiated cells are granular, and that as 

 differentiation proceeds, these granules unite to 

 form chains and threads (Fig. 31, B). The sex 

 cells, however, retain the chondriosomes in their 

 primitive granular form, and remain in an undiffer- 

 entiated condition situated in the posterior part of 

 the embryo among the entoderm cells. Tschaschkin 

 (1910), in the same year, came to a similar conclusion 

 from studies made with chick embryos. Rubaschkin 

 (1912) has also extended his investigations on guinea- 



