115 



they furnish on the osmotic pressure of organic fluids and 

 on the binding of tlie water molecule by protoplasmic sub- 

 stances. We shall summarize here some of the more rep- 

 resentative works, but we refer the readers to reviews on 

 the two subjects mentioned, for more complete data. 



1, Culture Media. The freezing point of fresh water 

 was found to be, in general, 0.03 or 0.04 of a degree lower 

 than that of distilled water. 



Backman and Runnstrom (1912) report that the water 

 from which they collected frog's eggs froze at - 0.060°. 



Bialaszewicz (1912) found a freezing point of -0.01° to 



- 0.02° for the tap water that he used for studying the 

 development of amphibian eggs. 



The freezing point of sea water, determined by various 

 authors, mostly at marine biological stations, was found 

 to vary from -1.09° at Kiel (Dakin, Biochem. Jour. S, 

 258, 1908) to -2.29° at Naples (Bottazzi, Arch. Ital. de 

 Biol., 2t>, 61, 1897). At the American biological stations 

 of Woods Hole (Mass.), Pacific Grove (Cal.) and Beaufort 

 (N. C), Garrey (1905) obtained respectively -1.81°, 



- 1.92° and - 2.04°. In a later work of the last mentioned 

 author (1915), the reader will find tables of the freezing 

 points of sea water at various dilutions and of solutions 

 of NaCl and MgCL at concentrations osmotically compar- 

 able to sea water. 



Jensen and Fischer (1910) give -0.42° as the freezing- 

 point of the ** physiological solution," that is, of a 0.7% 

 solution of sodium chloride. 



Of the substances used in culture media, sucrose was 

 found to lower the freezing point more than was expected 

 by the law of the freezing point depression. A gram 

 molecular solution freezes at -2.775°, according to Garrey 

 (1915). Loeb ("Artificial Parthenogenesis and Fertiliza- 

 tion," Chicago, 1913, p. 130) pointed out the biological 

 significance of this fact, which is usually attributed to a 

 hydration of the molecules of sucrose. For more data and 

 discussion see ^lorse, Frazer, Hoffman and Kennon {Am. 

 Che)u.Jour.,S0,^9,1906). 



