165 



The same author (1935) studied the completion of con- 

 gelation in amphibian muscles. He embedded the latter 

 in discs of gelatin gels, exposed them to various low tem- 

 peratures, and measured the amount of ice formed at the 

 surface of the discs. He found that most of the freezable 

 water froze between 0° and -5°, that about lO^r of the 

 total water froze between - 5° and - 20° and that less than 

 1% froze between -20° and -37.5°, at which temperature 

 freezing ceased. 



The duration of the freezing process at a given tempera- 

 ture is shown by an experiment of ^loran (1926) on a 43.7% 

 gelatin gel put to freeze at - 11°, the volume of which was 

 determined with a dilatometer. The increase in volume, 

 rapid during the first few days, soon became very slow, but 

 it ceased only after 26 days (Fig. 25). 



^55 



10 20 30 40 



Duration of freezing, in days 



Fig. 25. Increase in the quantity of ice formed in a gelatin gel exposed 

 for 26 days to - 11°. (From Moran, 1926.) The ordinates represent dila- 

 tometer readings. 



In all these investigations it was assumed, as a principle, 

 and this was subsequently observed as a fact, that con- 

 gelation is more complete when the temperature is lower. 

 But, it is also a principle and an established fact, as we said 

 above, that the velocity of formation of nuclei and of 

 growth of crystals is gradually reduced to zero when one 

 lowers the temperature. These two principles are in evi- 

 dent contradiction and one of them has to be sacrificed. 



