117 



results that he considers reliable — 0.1 of a degree differ- 

 ence, between the extremes, in the freezin<»' points of the 

 blood of 10 ducks and about 0.3 of a degree, between the 

 extremes, in 7 turkeys. 



Relation Between the External and 

 Internal ^1 e d i u m. The problem of the adjust- 

 ment of the fluids of the body to the external medium has 

 given rise to a series of observations on the comparative 

 freezing points of sea or fresh water and of the blood of 

 marine, fresh water or land animals. A first review of 

 the subject has been made by Hober ("Physikalische 

 Chemie der Zelle und der Gewebe," Leipzig, 1902, Chap- 

 ters 2 and 12). 



Since the publication of this review, Garrey (1915) 

 reported that the freezing point of the blood of several 

 marine animals, including large-sized fishes such as the 

 shark, was very near that of sea water. The freezing 

 point of fresh water animals, for example, fishes of the 

 Mississippi River, varied from -0.48° to -0.52° in 6 spe- 

 cies, and was, therefore, considerably higher than the freez- 

 ing point of the blood of marine fishes and definitely lower 

 than that of fresh water itself. 



The blood of the marine turtles, unlike that of other sea- 

 animals, had a freezing point of - 0.69°, that is, markedly 

 higher than that of the water in which they were living, 

 which was -2.04°. To study the possibility of an adjust- 

 ment of the internal to the external medium, in these ani- 

 mals, Garrey measured the freezing point of the blood of 

 two marine species left for 2 months in a tank containing 

 fresh water. He found the same value as for the animals 

 taken directly from sea water. However, some adjust- 

 ment in other animal groups, such as fishes, has been shown 

 by Garrey himself in some of his previous investigations 

 (1905) and also by other workers, in particular by Scott 

 (1913). 



The last mentioned author published, in 1916, a review 

 in which the results of numerous investigators are tabu- 

 lated. There are listed 111 species from the most impor- 

 tant phyla of the animal kingdom. 



