Depression of the Freezing Point of Water. 85 



if they are transferred into sea-water they form membranes and a 

 smaller percentage of them undergoes cytolysis. If the eggs re- 

 main a short time only in the soap solution, they all form mem- 

 branes, but few cytolyze after being transferred into sea-water ; if 

 they remain for a longer time, they all form membranes but cyto- 

 lysis follows very soon after the membrane formation. 



The question arises, why do the eggs form their membrane 

 only after they are transferred into sea-water ? This is due to the 

 alkaline reaction of the sea-water. If we make the sea-water 

 faintly acid by the addition of hydrochloric acid no egg forms a 

 membrane or undergoes cytolysis after being transferred into sea- 

 water, and if we make the solution of sodium oleate in sodium 

 chloride slightly alkaline by the addition of sodium hydroxide the 

 eggs form membranes while they are in the soap solution. 



If we allow the soap solution to act only long enough to cause 

 the membrane formation, but not long enough to cause cytolysis, 

 the eggs can be caused to develop larvae. We may from all these 

 experiments draw the inference that the development of the resting 

 egg is caused by a superficial or mild cytolysis, and that the 

 spermatozoon must carry a cytolytic substance into the egg, 

 possibly a trace of higher fatty acid. 



40 (378) 



On the depression of the freezing point of water due to 

 dissolved caseinates. 



By T. BRAILSFORD ROBERTSON and THEODORE C. BURNETT. 



\_Froin the Rudolph Spreckels Physiological Laboratory of the 



Ufiiversity of California.~\ 

 The question whether or not proteins possess, in solution, a 

 definite osmotic pressure has been the subject of much controversy. 

 The original investigations of Graham ' appeared to indicate that 

 colloids in general exert a high osmotic pressure. Subsequent 

 investigators, however, attribute these results to an admixture of 

 crystalloids and the investigations of Sebanejew,^ Tamman,* 



'Graham: Phil. Trans. Roy. Soc, 1861, cli, 183. 



'Sebanejew: Berichte d. deut. chem. Gese/l., 1890, xxiii, 87; 1891, xxiv, 558; 

 xxvi, 385. Sebanejew and Alexandiow : Joui n. of the Russian Phys.-chem. Soc, 

 1891, p. 7; quoted ahtr Maly' s Jahresber.f. Tiac/ient., 1891, xxi, II. 



'Tamman : Zeit. f. physikal. Chem., 1896, xxi, iSo. 



