94 



Maynard M. Metcalf on the 



After having examined several hundred blastomeres, all 

 showing the intra-protoplasmic bodies under discussion, I 

 have selected a single bla?tomere to figure and describe, not 

 because there are not many others showing a similar con- 

 dition, but because this seems sufficient to establish the point. 



The blastomere figured is one of five appearing in a section 

 of an embrj'o of S. hexagona at that stage of development 

 when the follicular epithelium of one half the surface of the 

 embryo is most rapidly proliferating — about the stage shown 

 in Brooks's fig. 2, pi. xi. The arrow indicates the direction 

 of movement of the follicle-cells as they wander into the 



/. 







ft^r^^ 



Portion of a section of a young- embryo of Salpa hexagona, sliowing one 



blast omere and fifteen mi grated follicle-cells. 



5/=blastomere ; J\"= nucleus of blastomere ; a, b, c, d, e,f, g, h, j, A = 



nuclei of follicle-cells ingested by tbe blastomere. 



centre of the embryo, where, as described by Brooks, many 

 of them degenerate. The figure is carefully drawn with a 

 Leitz ^2 immersion objective and a number 8 compensating 

 ocular. 



The large blastomere, BI, has a very large nucleus, N, and 

 evenly granular protoplasm, which does not stain deeply with 



