STRUCTURE AND DEVELOPMENTAL RATE 



143 



those eggs which have been subjected to the higher temperature will 

 gain a decided advantage as compared with the lower-temperature 

 groups. 



At 5 days old, the control showed the heart beat just beginning, 

 but no circulation. Lot Bi, after 3 days at room temperature, con- 



8 



Fig. 7 Three specimens 4 days old, having been 24 hours at room temperature 

 following a stay of 70 hours at 7°C. The upper outline shows a disc-like cap 

 flattened down on the yolk-sphere; the middle one, a high segmentation cap; 

 and the bottom specimen has a cell mass comparable to a normal 12-hour stage. 



Fig. 8 Top and lateral views of 4-day specimens, having been 24 hours at 

 room temperature following 70 hours at 8°C. These segmentation masses are 

 very abnormal and are distorted by the presence of a huge vacuole, V. 



tained short embryos on the surviving eggs, but the majority of eggs 

 failed to develop at all after being removed from the cold. Lot B2 

 had germ-rings onh' about one-half, or a little more, over the yolk- 

 sphere. Thus the one day longer in the refrigerator had caused these 

 to be far behind B]. 



