TO THE EMBRYOLOGY OF AMPHIBIA. 37 



of the egg has begun. If pigment were absent in the eggs 

 of Rana and Bufo, similar relations could no doubt be made 

 out. 



9). As to the location of the embryonic body, the results 

 of the present investigation are in entire accord with the views 

 of Assheton ('94a), and Eycleshymer ('98). The anterior half 

 of the embryonic body is formed on the upper hemisphere of the 

 egg, and the posterior half on the lower hemisphere. I can not, 

 however, in any way make out that the two halves of the embryonic 

 body are in reality formed from the two separate centers of the 

 formative area, as was supposed by these two authors. And as to 

 the orientation of the embryonic axis, I agree in the main with 

 Kopsch's statements : — " Und dass die von Pol zu Pol gezogene 

 Axe der Furchungsstadien nicht die dorsoventrale Axe des Em- 

 bryos ist, sondern dass sie beim jungen Embryo schräg von 

 caudal oben nach cranial unten verläuft," (p. 21, '00). I have 

 only to point out that according to the present observations the 

 head portion of the young embryo is turned always upwards (not 

 " unten ") and at the same time the caudal portion is turned 

 downwards (not " oben "). 



I have described above how I found in two Bufo eggs 

 that the axis of the embryonic body coincided with the plane 

 of the second cleavage line. According to many previous in- 

 vestigators, the coincidence ought to be with the first cleavage 

 plane rather than with the second, while some recent writers, 

 as Jordan and Eycleshymer ('946), entertain the view ex- 

 pressed in the following quotation : — " It seems to us a more 

 reasonable supposition that the direction of the early cleavage 

 planes and the embryonic axes have not vital connection, and 



