184 WHAT 18 LIFE 



in his Brownian Movement and Molecular Reality^ 

 and which the Tyndall cone reveals. The movement 

 of the spermatozoa in this case is governed by the 

 attraction of the egg. It is directed at the egg. To 

 be told that the movement is "mechanical" or a 

 positive chemotaxis, does not enlighten one. (It is 

 well known that cytologists do not deem the cause 

 of the uniting of the spermatozoon and the egg to 

 be adequately stated by describing it as due to a 

 "positive chemotaxis" or an accidental coming to- 

 gether or an undefined "attraction. "^^) I hold that the 

 movement of the spermatozoon here is accounted for 

 on the theory that the spermatozoon is an "ion" (with 

 an intraatomic electrical system, as defined) that is 

 attracted by another "ion" (the ovum). Obviously, 

 according to this view of the germ-cells, fertilization 

 is governed by very exact physicochemical laws. This 

 must be borne in mind in interpreting the great 

 variety of phenomena and factors (such as location 

 of the egg, etc.) exhibited by the process. An "acci- 

 dental" bringing together of spermatozoon and egg 

 well may be necessary before the attraction between 

 them can become manifest: two bodies constitu- 

 tionally may have a very powerful attraction for each 

 other, but whether this attraction is capable of oper- 

 ating is determined by absolutely definite and rigid 



" See Edmund B. Wilson, The Cell in Development and Heredity, 406, 407. 



