454 WM. E. KELLICOTT 



in some instances just forming, in others clearly formed. After 

 eight and one-fourth days at 8-1 0°C. these were removed to the 

 room; nearly all were alive but development had continued very 

 slowly so that none showed beating hearts (normally the heart 

 begins to pulsate about twenty-four hours after the establish- 

 ment of the optic vesicles and the closure of the germ-ring). 

 Some were already abnormal at the time of their removal, many 

 others became abnormal as development in the room continued, 

 but about two-thirds hatched normally after eight to eleven days 

 longer. 



It is interesting to compare certain of these observations with 

 those of Loeb ('15) who found that treatment with a tempera- 

 ture somewhat lower than any I used, namely 7°C., w^as followed 

 by no abnormalities in development. At that temperature 

 Loeb found that ''the newly fertihzed eggs can live for weeks 

 . . . . without being injured" and that they ''developed 

 very slowly but no abnormal embryos were observed, although 

 some of the eggs were kept at a temperature of 7°C. for four 

 weeks" (p. 62). Loeb also used temperatures much lower than 

 any with which I worked and found that even at 0-2°C., if the 

 treatment were not prolonged more than four to seven and one- 

 half hours, and if stages from the time of insemination to about 

 four cells were used, only 20-30 per cent became abnormal upon 

 transference to the room; longer treatment increased the mor- 

 tality considerably, none surviving forty-eight hours at this 

 temperature. If the eggs were first allowed to develop fifteen 

 hours at a normal temperature (stage given as about one hun- 

 dred and twenty-eight cells, although at the usual laboratory 

 temperature of 22°C. this stage is reached about five hours after 

 insemination) Loeb found that after two days at 0-2°C. normal 

 development was still possible, although he does not state that 

 abnormal development did not also occur in some individuals. 

 But he found that if the embryo is once formed before treat- 

 ment, it survives weeks of subjection to 0-2°C. "without any 

 injury." "As soon as it is put back to room temperature it 

 continues to develop" (p. 59). 



