STUDIES IN THE PHYSIOLOGY OF SPERMATOZOA. 211 



the higher carbon dioxide and hydrogen ion concentration that 

 is soon reached as a result of the tremendous activity of sperma- 

 tozoa in "egg water." 1 



After removal of the carbon dioxide, "egg water" can still 

 agglutinate sperm. 2 



Schiicking also found that: "Zwei Tropfen des nicht dialy- 

 sirten sauren Extracts oder ein bis zwei Tropfen d6s Riickstandes 

 vom Dialysat, mit einem Tropfen 3 per cent, iger Na 2 CO 3 Losung 

 und fiinf Tropfen destillirten Wassers agglutinirten das Sperma 

 noch, obgleich sie neutrale Reaction zeigten" (Schiicking, A., 

 1903, p. 61). Accordingly spermatozoa that are added to egg 

 water, where they are very active, produce a large amount of 

 carbon dioxide. This is also true when spermatozoa are put into 

 alkaline sea water. Unlike the former case, however, the carbon 

 dioxide produced is not so effectively neutralized in the case of 

 egg water, and the acidity of the solution rapidly increases. This 

 is followed, as has been shown, by a decreased activity on the 

 part of spermatozoa and a consequent increase in the length of 

 their life. 



The effect of egg water upon the fertilizing power of sperma- 

 tozoa, is, therefore, not so very dissimilar to the effect of the other 



1 The writer is aware of several other possible interpretations of the observation t 

 that (a) the ability of "egg water" to preserve the life of the sperm is greater than 

 is sea water of exactly the same hydrogen ion concentration and that (b) a very 

 concentrated "egg water" will often be less effective in preserving life than a less 

 concentrated "egg water." For if the "agglutinating substance" be protein 

 in character, as the investigation of Schucking (Schiicking, A., 1903) (who found 

 the "agglutinating substance" in the undializable fraction of an egg extract) and 

 of Richards & Woodward (Richards, A., and Woodward, A. E., 1915) suggests 

 the "Studies in the Fertilization of the Eggs of a Sea Urchin. (Slrongylocentrotus 

 pnrpuratus) by Blood-Sera, Sperm, Sperm-Extract, and other Fertilizing Agents" 

 of T. B. Robertson (1912) may possibly explain these observations. He observed 

 that the "potency of the serum" in initiating either the cytolysis or the develop- 

 ment of the egg "obtains a maximum at a dilution of about 1/16" and that "serum 

 of this dilution frequently agglutinates the eggs, causing them to aggregate in large 

 clumps within a few seconds" (Robertson, T. B., 1912,' p. 71). In higher con- 

 centration the proteins inhibit the imbibition of water by the eggs. 



2 That the "agglutination" phenomenon is not independent of the hydrogen 

 ion concentration of the solution has been shown by Loeb. In acid solution 

 where the sperm are inactive, the "agglutination" cannot occur. The "agglutina- 

 tion" is strongest in solutions slightly more acid than is ordinary sea water but 

 "the clusters" disappear the more rapidly the more alkaline the solution. 



