^s'2 



sm's is, ill iicncrnl, lower lliaii llial ot" dead inalcrial. l.'\ 

 Living- tissues sometinics pii'sciil two t'rcczini!,' jioiiils, one 

 of wliich is proliably that ot" tlu' iiiterccllulai', the other, 

 that of the exuded iiiti'aeelhihir fluids. 



14. Till' uTowlli of crystals is less ra])i(l when the tem- 

 IX'i-ature is lower. 15. The iioii-i)a]"allel variations in tlie 

 velocity of formation of nuclei and in the velocity of 

 growtli of crystals, in terms of temperature, result in a 

 dependence of number, size and form of crystals on tem- 

 ])eratiire. 1(). The velocity of growth of ice crystals is 

 about 65 mm. per second at -8"; the addition of solutes 

 reduces this velocity (39''^ gelatine reduces it 350 times). 



17. The separation of water during the congelation of 

 solutions, suspensions and colloids can often be observed 

 under the microscope. 18. In a gel cooled slowly, w^ater 

 comes out to the surface where it freezes in a compact 

 mass, while, on a more rapid cooling, internal congelation 

 takes place. 19. Internal congelation of gels sometimes 

 results in the formation of spherulites within which one 

 can observe two separated phases, ice and dehydrated gel, 

 in alternating concentric layers. 20. In coagulated mate- 

 rial, in porous structures and in tissues, water exudes to 

 the surface during freezing and forms tiny ice columns 

 which fuse laterally into ribbons or plates. 21. (^avities 

 within frozen tissues are found filled with ice which has 

 separated from the surrounding cells ; intercellular spaces, 

 in compact tissues, play the role of cavities and lens-shaped 

 masses of ice accumulate in them. 22. In the case of sin- 

 gle cells exposed to slow freezing, water exudes and con- 

 geals at the surface. 23. The Avithdrawal of water during 

 freezing has been observed also in cellular constituents, in 

 particular in nuclei, possibly in chromosomes. 



24. The freezing curve of an ideal liquid consists of a 

 linear and of two exponential portions. 25. The freezing 

 curve of a solution consists of a hyperbolic, a linear and 

 two exponential portions. 26. The plateaus of the freez- 

 ing curves of most living tissues occupy a lower position, 

 are shorter, less uniform and more inflneiiced by cooling 



