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THE AMERICAN NATURALIST [Vol. XL V 



latter seem to be limited because of their absence to the 

 performance of vegetative functions, and the germ cells 

 appear to have the power of reproduction because of 

 their presence. 



A recent paper by Elpatiewsky (1909) deals with the 

 early embryonic development of the arrow worm, Sag- 

 itta. This investigator finds that, at the stage when the 

 two pronuclei are in the center of the egg, a body appears 

 at the vegetative pole lying near the periphery (Fig. 3, 



A). This body, which is termed "besondere korper," 

 consists of coarse granules which do not stain quite so 

 deeply as the chromosomes. During the first four cleav- 

 age divisions the "besondere korper" does not divide, 

 but is always to be found in one blastomere. In the 

 fourth division the blastomere which contains this body 

 divides unequally; the larger cell is destined to produce 

 the entoderm (Fig. 3, B, E) • the smaller cell, which con- 



