156 



w» H »'>»>'«x» X » X « . « 



12 



16 Mm. 



2 4 6 8 10 



Fig. 19. Coininiiativc freezing curves of a solution (x x x) and of a sus- 

 pension (. . .) of gelatin. (Curves drawn according to the data of Fischer 

 and Bobertag, 1909.) 



4. Fn'cziug Curves of Tissues. For a description and a 

 discussion of the freezing curves of plant tissues, we refer 

 the readers to ^^liiller-Thurgau (1881 and 1886), Voigt- 

 lander (1909), Maximov (1914), Walter and Weismaim 

 (1935), and Luyet and Gehenio (1937). Some freezing 

 curves of animal tissues were studied by Jensen and 

 Fischer (1910) and some of entire animals by Cameron and 

 Brownlee (1913) and by Weigmann (1936). These curves 

 were established for the information that they furnish on 

 such problems as the position of the freezing point, the 

 quantity of water withdrawn at a given temperature, the 

 mechanism of death ])y freezing, the relations between the 

 death i^oint, the freezing point and the quantity of ice 

 present, the range of subcooling, and the existence of a 

 eutectic point. We treated above the problems concern- 

 ing the freezing points ; those related to subcooling will be 

 reviewed in llie next chapter; the other jn-oblems men- 

 tioned will be studied here. 



Living and Dead Tissues. The following dif- 

 ferences were reported in the freezing curves of living and 

 of dead tissues, stndii'd under otherwise comparable con- 



