158 PHYSICAL CHEMISTRY 



found that they are attracted by C0 2 and this observation has 

 been confirmed (McClendon, 1914 e), it seems probable that it 

 is the C0 2 given out by the eggs that attracts the sperm 1 , and 

 hence it is not at all specific. Mammalian sperm appear to be 

 attracted by cells of the wall of the uterus. 



F. Lillie claims that the sperm cannot unite -with the egg unless 

 a substance which he calls fertilizin (a specific agglutinin?) is 

 present to accomplish the union. When the sperm are treated 

 with the agglutinin extracted from the ripe eggs of the same 

 species, they become motionless with their heads adhering to- 

 gether. F. Lillie claims that these agglutinins are specific, but 

 J. Gray (1915) has substituted hydroxyl ions or trivalent cat- 

 ions. Gray says that cerous chloride is as effective as the 

 agglutinin extracted from the egg. He says further that OH 

 ions and trivalent cations not only agglutinate but also activate 

 the sperm, and that H ions, which reduce their activity, do not 

 agglutinate. This inactivation by acids is reversible. F. Lillie 

 had already stated that alkalis cause agglutination and also that 

 acids cause aggregation. Since the attempts of Arrhenius and 

 others to reduce immunochemistry to a physicochemical basis 

 have been so hampered by lack of pure samples of the immune 

 bodies, the discussion of the relation of fertilization to immuno- 

 chemistry seems out of place at present. 



The sperm does not need to penetrate the egg in order to cause 

 cell division. Kupfelweiser, Bataillon (1910) and Brachet ob- 

 served that the sperm needed merely to scratch the surface of 

 the egg in order to make it segment. The sperm of foreign 

 species usually cannot enter the egg, yet they may cause it to 

 develop. This seems to indicate that the sperm 'causes a super- 

 ficial change in the egg. Loeb called this a superficial cytolysis. 



R. Lillie observed that some of the red pigment comes out of 

 Arbacia eggs when they are treated with parthenogenic agents, 

 and concluded that fertilization is accompanied by increase in 

 permeability. Lyon and Shackell (1910 b) showed that some 

 of this pigment came out of the eggs on fertilization. 



In order to test this conclusion, the electric conductivity of 

 sea urchin eggs immediately before and after fertilization was 

 measured (McClendon, 1910 c, e). The egg is surrounded by 

 a mucous jelly and after fertilization a membrane, the fertiliza- 



