STUDIES IN THE PHYSIOLOGY OF SPERMATOZOA. 177 



In 1900 Duller observed the "agglutination" or "cluster for- 

 mation" of Arbacia sperm in water that had contained eggs of 

 the same species and suggested that "a tactile stimulus appears 

 to play a part in the phenomenon" (Duller, A. H., 1900, p. 387). 

 As the "aggregation" of sperm by carbon dioxide has been sup- 

 posed to be due to chemotaxis, so also has the "agglutination" 

 of sperm by "egg water" (de Meyer, J., 1911, Lillie, F. R., 1913; 

 Glaser, O., 1914). The phenomenon of "agglutination" will be 

 discussed in another place. The configuration of Arbacia sperm 

 in "agglutination" and of Nereis sperm in "aggregation" is not 

 dissimilar (Lillie, F. R., 1913). 



In 1902 Duller described the accumulation of inactive sperm 

 in an oxygen gradient. This has been characterized as the con- 

 verse of Lillie's "ring formation" in a gradient of carbon dioxide 

 (p. 12). Duller explained the phenomenon as the result of the 

 differential activity of spermatozoa in the gradient. He was, 

 however, unable to account for the "clear zone" that occurs in 

 the configuration. In consequence subsequent workers have 

 had recourse to the accessory hypotheses that have been dis- 

 cussed. While there is no a priori reason for believing either 

 that spermatozoa are not activated in certain concentrations of 

 carbon dioxide or that they are not chemotactic to carbon dioxide, 

 it should be pointed out that no positive evidence for either as- 

 sumption has ever been demonstrated. 1 



III. THE RELATION BETWEEN THE ACTIVITY AND THE LONGEV- 

 ITY OF SPERMATOZOA. 



Increase in the activity of spermatozoa leads to a decrease in 

 the length of time during which spermatozoa exhibit activity. 

 This was observed by Koelliker, who remarked, regarding the 

 effect of the alkali salts of carbonic acid, that they behaved much 

 as the caustic alkalies in that: "Sie erregen die Samenfaden leb- 

 haft, doch dauert deren Dewegung nicht lange" (Koelliker, A., 

 1856, p. 239). Koelliker emphasized that this activation oc- 



1 "Dewitz, Buller, and the writer have vainly tried to prove the existence of a 

 positive chemotropism of spermatozoa to eggs of the same species" (Loeb, J., 

 1916, p. 93). 



