480 STANLEY C. BALL 



The question as to whether any function is to be assigned to 

 the mitochondrial mass in Paravortex can be more intelhgently 

 considered after the conditions under which it exists as long 

 as it remains visible have been fully described. 



At a time approximately coincident with the appearance of 

 the mitochondrial mass the cytoplasm of the oocyte becomes 

 less dense, while its general color changes from the bluish gray 

 of the oogonium to a more neutral tmt bordering on the brown. 

 So far as can be observed with the highest magnification obtain- 

 able this change in color is due not to an intercalation of yellow- 

 ish particles but to a change in the staining reaction of the cyto- 

 plasm as a whole. The simultaneous increase in the amount 

 of the latter is not caused by deposition of distinct deutoplasm 

 spheres. At any rate there is no addition of particles wHch 

 stain differently from the cytoplasm. Neither is growth the 

 result of vacuolization ; the mature oocytes in well preserved 

 material never contain vacuoles. The only change observable, 

 in so far as the consistency of the cytoplasm is concerned, is 

 a tendency of the minute granules to become grouped in slightly 

 larger units of irregular form. The appearance presented to 

 the eye is that of a multitude of small flakes and flocculent 

 bars between which intervene irregular colorless regions which 

 in size closely approach that of the stained particles (fig. 7). 

 These spaces become somewhat more conspicuous as the oocyte 

 reaches maturity. It has been impossible to detect in them 

 the 'mitosomes' which Wilson and others have described as 

 lying in the protoplasmic trabeculae between the alveoli of the 

 echinoderm egg. 



Although, as pointed out above, no conspicuous spheres are 

 to be found in the cytoplasm of Paravortex, it is apparent that 

 the particles which are added must be of the nature of deuto- 

 plasm. Their distribution is remarkably homogeneous; in 

 other words, the eggs are homolecithal or alecithal. 



Nourishment enters the ovarian cells by osmosis from the 

 parenchyma surromiding them, not, as Patterson states, in 

 the form of particles ingested from the vitellaria which at some 

 points come into close proximity with the ovary. The vitelline 



