120 



freezing points of tlic yolk of tlic cliicken (',«;■<;• (luriui;' its 

 formation and development : 



Ovarian egg, 4 to 1 cm. in diameter : - 0.632° 

 Ovarian egg .'> em. in diameter : - 0.613° 



Eggs half way down the oviduct : - 0.585° 

 Freshly laid eggs: -0.564° 



Embryo at the 8th day of inc. : - 0.496° 



Embryo at the 18th day of inc. : - 0.601° 



Blood of the adult : - 0.635° 



So, when it is detached from the ovary, the egg has about 

 the same freezing point as the blood. During the growth 

 period, the freezing point increases to a maximum. Dur- 

 ing embryonic development, it gradually drops again to 

 its original value. 



The amniotic fluid froze at - 0.582° and this point did not 

 change significantly up to the 18th day of incubation. The 

 freezing point of the allantoic fluid, on the other hand, 

 rose from - 0.513° to - 0.431° from the 8th to the 18th day. 

 The egg white froze at - 0.458° in fresh eggs and at - 0.444° 

 after 8 days of incubation. 



The same au,thor reported a change in the freezing point 

 of the frog's egg from -0.444° for the ovarian egg, to 

 -0.294° on the 3rd day after fertilization and to -0.382° 

 12 days later. The blood of the adult frog froze at - 0.479°. 

 According to Backman and Runnstrom (1912), the cycle 

 of changes of the freezing point in the frog's egg and 

 embryo {Bana teniporaria) is as follows: 



Ovarian egg : - 0.48° 



Fertilized, unsegmented egg : - 0.045° 

 Stage of crescentic blastopore : - 0.215° 

 Stage of spherical blastopore : - 0.215° 

 Embryo, 5 days old : - 0.230° 



Larvae, 20-25 days old : - 0.405° 



Serum of the adult : - 0.465° 



These data confirm the general results obtained by pre- 

 vious investigators and, furthermore, they point out a 

 remarkable rise of the freezing point at the time of fer- 

 tilization. 



