222 HUBERT DANA GOODALE 



is only 130° from the blastopore. The length of the embryo, 

 then, is somewhat variable. 



There is still another sort of evidence to show that the anterior 

 connective lies anterior to the upper pole. Its cells have small 

 yolk granules. Only a very small region of ectoderm anterior 

 to the connective has these granules. Now, since the granules 

 maintain their original position until the neural folds begin to 

 develop, it follows that the neural folds lie anterior to the upper 

 pole. 



There are two eggs among the ones marked about the equator 

 (see below) in which the embryo apparently formed in greater 

 measure than is usual on the lower hemisphere. The explana- 

 tion of one of these cases is probably connected with the fact that, 

 after the eggs were marked and placed on the inclined mirror, the 

 primary egg axis failed to become perpendicular. 



The case of the other egg is not so clear. There is nothing 

 exceptional about the position of the blastopore, although the 

 marks dorsal to the lip failed to extend into it. But the anterior 

 connective appeared just above the equator. That is, it was a 

 short embrj^o, not over 130° in length. Two days later, the imper- 

 fect embryo lay on top of the egg, but to one side. This embryo 

 is probably comparable with the short one mentioned above. 

 It is interesting to note that a short embryo may form its anterior 

 connective in a position similar to that of the frog. 



The series in which both these eggs occurred showed more 

 extensive movements of the blastopore than the other series of 

 this year and moreover, nearly all the embryos lay at one side 

 of the upper hemisphere. 



Since the supposition that the embryo of the frog was formed 

 in the upper hemisphere as maintained by earlier workers, was 

 shown by Pfliiger and Roux to be incorrect, numerous other work- 

 ers have attempted to demonstrate the position of the embryo. 

 Their methods have consisted either in preventing the egg from 

 rotating, or in puncturing its surface. The results fail to agree, 

 but I believe this disagreement can be explained in one of two 

 ways, i.e., either it is due to preconceived ideas upon the subject, 

 or more likely to actual differences in the forms used. In general, 



