SEX AND THE INDIVIDUAL 187 



sion of a new river to that which has been dammed. 

 The force liberated by their conjunction is sufficient 

 to tear away all barriers, and from the instant of this 

 release their mingled forces rush on, with gradually 

 slackening energy, to the fulfillment of their destiny. 

 The process of fructification of the female by the 

 male cell is thus in its essence a stimulus to develop- 

 ment in which new possibilities of developmental 

 variety are rendered possible by the fusion of two 

 streams of hereditary qualities. So sexual repro- 

 duction, by virtue of this fusion of diverse forces, 

 makes possible new and elaborate types of beings 

 that are not imaginable under any observed system 

 of unisexual reproduction. In unisexual organisms, 

 as, for example, the paramecium, there is a sort of 

 theoretical immortality, for as each organism divides 

 by budding, there can be no death so long as some 

 representative of the type exists, but this form of 

 immortality clearly involves a lack of individuality. 

 Moreover, under such a system, only trivial varia- 

 tions appear, in general, possible, and hence the 

 path of organic progress is fatally barred. Indeed, 

 even the continuation of the budding process ap- 

 pears to be limited to some hundreds of generations, 

 unless occasional contacts occur (perhaps foreshadow- 

 ing vaguely a sexual union) with members of another 

 family, in the course of which contacts there is a 

 streaming of protoplasm from one cell into another. 

 Indeed, an actual fusion of cells may occur in which 

 there takes place an exchange of nuclei. Even in 



