198 CORA J. BECKWITH 



yolk takes the plasma stain, while the globules of the compound 

 spheres are the only bodies in the egg which take the hematoxylin. 



Since the globules of the compound yolk-spheres are of similar 

 size and may take the same stain as the mitochondria (the violet 

 of Benda's stain) they at first suggest nests of dividing mito- 

 chondria. This is an impossibility however, since the compound 

 yolk-spheres are the most conspicuous structures in eggs fixed in 

 killing fluids which dissolve the mitochondria (picro-acetic). 



The mitochondria are so identified because of their rod-like 

 shape and their typical mitochondrial behavior; that is, they 

 dissolve in fixatives containing acetic acid, do not dissolve in 

 alcohol, are darkened by osmic acid, and give the typical response 

 to the so-called mitochondrial stains (Benda, Bensley or Altman, 

 and iron-hematoxylin) . In living material they are highly refrac- 

 tive bodies which take Janus green as a vital stain. 



C. HISTORY OF THE YOUNG EGG, BOUQUET-STAGE 



The youngest eggs studied were found in the proliferating area 

 of the stalk of the gonophore. Here the entoderm cells are smaller 

 than those of other regions, their protoplasm is not vacuolated, 

 and their nuclei are more deeply staining. The eggs, when 

 differentiated from the surrounding entoderm cells, are somewhat 

 larger and have nuclei in the bouquet-state; a nucleolus is present 

 in which the chromatin-loops center (figs. 1 b, 2,). A slightly 

 later stage shows the nucleolus in which the chromosomes center, 

 pressed against one end of the nucleus (fig. 3). The origin of 

 these cells was not determined. Since they are evidently the 

 result of a recent division (they are usually found in pairs) it 

 seems probable that they are the product of an oogonial division 

 (fig. 1). The egg cells are conspicuous in this stage, since the 

 chromatin and nucleolus take the basic stains intensely. The 

 protoplasm, which is a very thin homogeneous layer around the 

 nucleus, stains but lightly with plasma stains and thus contrasts 

 strongly with the nucleus. This stage corresponds to Schaxel's 

 'pre-emission stage' The structure is the same, whatever fixative 

 is used. No attempt to study synapsis was made, although many 

 cells showed some evidence of double threads (fig. 1 a). 



