LOW TEMPERATURE DEVELOPMENT OF FUNDULUS 453 



unfixed eggs. The results of the detailed study of sections of 

 such eggs, which will perhaps enable me to determine more pre- 

 cisely the effects of the cold, will be reported separately at a 

 later time. 



Upon removal to room temperature, after having been some 

 hours or days in the condition just described, many eggs failed to 

 develop, and after some hom*s longer died without undergoing 

 any apparent structural changes. On the other hand, most of 

 those eggs in which there were present considerable masses of 

 the darker granular material showed some processes of develop- 

 ment, exhibiting before their death every degree and form of 

 abnormality, from irregular protoplasmic masses, suggesting 

 cellular structures, to hatched larvae, well-formed though usually 

 abnormal in some respect. In a very few instances (three were 

 noted) normal larvae resulted from the development of these 

 dark, irregular, non-cellular masses. 



When the eggs were allowed to develop normally for a few 

 minutes (fifteen to thirty) before refrigeration, the general re- 

 sults did not seem to be markedly different, although there are 

 some indications that fewer embryos developed normally. 



Two lots of eggs were allowed to develop normally for twenty- 

 two to twenty-three hours after insemination before they were 

 placed in the refrigerator at about 11°C. At this age and at 

 room temperature, the germ-ring is formed and just commencing 

 its extension around the yolk. From a fourth to a third of these 

 were dead after twelve hours in the refrigerator. Most of the 

 remainder, after eleven days in the cold were alive, and upon 

 transference to the room developed, some into normally hatching 

 larvae, others into larvae with various defects and abnormalities, 

 some very pronounced. Upon removal after twenty-one days 

 many died and. nearly all of the survivors developed very ab- 

 normally; but two hatched normally after ten to eleven days in 

 the laboratory, i.e., thirty-two to thirty-three days after fer- 

 tilization. 



One lot of eggs was allowed to develop for forty-three hours 

 before refrigeration at about 10°C. At this age the germ-ring is 

 just closing, the embryo is well established and the optic vesicles 



