228 L. V. HEILBRUNN 



fertilization, shows no signs of alteration. On the other hand, the 

 lipoids of the egg interior are oftentimes visibly changed. This 

 is easily seen after the egg is centrifuged, for the cytoplasmic 

 lipoids then become aggregated at one pole of the egg, forming 

 there a small polar accumulation known as the gray cap. After 

 the egg had been treated with one of the substances used in the 

 above experiments, it was often noted that the gray cap appeared 

 pale and indistinct. Sometimes the gray cap was apparently 

 absent. Thus these substances which prevent gelation possibly 

 produce their effect by acting on the lipoids of the egg. 



Even before Wilson had shown that ether prevented the ap- 

 pearance of asters and spindle, 0. Hertwighad made the observa- 

 tion that this effect could be produced by low temperatures 

 (—2° to —3°) without otherwise injuring the egg. My views, 

 therefore, demanded that such low temperatures have a liquefy- 

 ing effect on the cytoplasm. This was fully borne out by ex- 

 periment. 



June 24th. At 4:36 p.m., eggs fertilized sixteen minutes previously 

 were exposed to a temperature of —3°. Fifteen minutes later (at 4:51 

 P.M.), the eggs were removed from the cold, and after an interval of two 

 minutes they were centrifuged simultaneously with control eggs, also 

 fertilized at 4:36 p.m., but not exposed to cold. The handle was turned 

 40 times in 30 seconds. On examination, the untreated control eggs 

 showed no stratification whatever, whereas the eggs exposed to cold 

 showed the various stratification zones plainly. 



Not only does cold exert an antigelatinizing action on fertil- 

 ized eggs, but it has a similar liquefying effect upon the cytoplasm 

 of unfertilized eggs. 



June Blj-th. Some unfertilized eggs were exposed to a temperature 

 of —3°, and after ten minutes they were centrifuged simultaneously 

 with normal eggs, the centrifuge handle being turned 21 times in 15 

 seconds. Both sets of eggs showed stratification. In the normal eggs, 

 however, the granular zone was not distinct from the pigment zone, 

 whereas in the cold-treated eggs the pigment granules had migrated 

 more completely, thus effecting a separation between granular and 

 pigment zones. 



The question now arises as to how this antigelatinizing effect of 

 cold is produced. Obviously it cannot act act as a lipoid sol- 

 vent. The idea suggested itself, however, that cold might pro- 



