366 



BERTRAM G. SMITH 



we assume that the control of the direction of entrance of the 

 spermatozoon was faulty and that the direction of first cleavage 

 affords an index to the real direction of fertilization, we still find 



Tig. 3 Diagrams showing the direction of the median plane of the gastrula in 

 sixteen eggs of Cryptobranchus allegheniensis in which an attempt was made to 

 control the direction of entrance of the spermatozoon; the direction of first 

 cleavage, also, is indicated. The eggs are shown in polar view; the seminal fluid 

 was applied to the edge of the germinal disc on the right-hand side of the egg. 

 In each egg an arrow, pointing anteriorly, shows the direction of the median 

 plane of the gastrula; the position of the blastopore is indicated by a broken 

 curved line. 



that there is no uniform relation between the entrance-path of 

 the spermatozoon and the median plane of the gastrula. 



Indirect evidence in support of this conclusion is furnished by 

 the results set forth in the next section. For it will be shown that 



