BILATERALITY IN CRYPTOBRANCHUS 



371 



A microscopical examination of the stained substance of the egg, 

 twenty-four hours after the application of the stain, showed that 

 the cytoplasm, and not the yolk granules, takes the stain. 



Fig. 14 Nine eggs of Cryptobranchus allegheniensis in the early gastrula 

 stage, inverted to show the vegetal hemisphere; the plane of first cleavage has 

 been marked by tying a silk thread around the egg. The figures were drawn 

 with the aid of a camera lucida. 



In order to mark the direction of first cleavage, eggs were taken 

 shortly before the appearance of the second cleavage furrow; 

 at this time the first cleavage furrow had not quite reached the 

 equator. Two small spots were made on opposite sides of the 



