EMBRYOLOGY OF CRYPTOBRANCHUS 115 



in the region of the future animal pole. But scattered throughout 

 the cytoplasm are occasionally to be found other bodies, resem- 

 bling the vitelline bodies but more irregular in form and staining 

 very faintly. While it is possible that these bodies are different in 

 kind from the brilliantly-staining vitelline bodies, their appear- 

 ance suggests that they are stages in the degeneration of the latter. 

 The faintly-staining bodies, though seldom numerous, are more 

 frequently found in regions poor in deeply-staining vitelline 

 bodies. These observations enable us to offer an explanation of 

 the distribution of vitelline bodies, alternative to the theory of 

 migration: a wave of development of vitelline bodies, followed 

 by a wave of degeneration, may sweep from the inner to the outer 

 hemisphere of the ovocyte. But whether migration is real or 

 only apparent, the fact remains that the region of most abundant 

 deeply staining vitelline bodies has shifted from the vicinity of 

 the future vegetal to the future animal pole of the ovocyte. This 

 change is perhaps an expression of polarity; if so, it is the first 

 indication of polarity that I have observed. However, it is not 

 at all certain that polarity is not present at an earlier period; 

 in particular the history of the chromatin has not been sufficiently 

 studied, moreover it is of course possible that a physiological 

 polarity of the cell may precede its manifestation in a visible 

 form. 



In the ovary of a 34 cm. female, fixed in Flemming's solution, 

 the distribution of vitelline bodies is much the same as noted in 

 the 30 cm. female; in form the vitelline bodies are sometimes oval 

 or irregular, but never mulberry-shaped as is sometimes the case 

 with Zenker's. 



In the ovary of a 35 cm. female, yolk granules are beginning to 

 form in the most advanced ovocytes; other ovocytes nearly as 

 large contain no yolk. In neither of these two stages are vitel- 

 line bodies in the typical condition present, but they are sometimes 

 found undergoing a process of degeneration — they lose the inten- 

 sity of their staining reaction, become irregular in form, and dis- 

 appear. The disappearance of the vitelline bodies at the time of 

 the formation of yolk suggests a correlation between the two phe- 

 nomena; but so far as I have been able to observe, the final stages 



JOURNAL OF MORPHOLOGY, VOL. 23, NO. 1 



