76 THE PSYCHIC LIFE 



that take place, after copulation, between the sperma- 

 tozoid and the ovule. 



There are numerous reasons for comprehending a 

 study of the generative elements within a general in- 

 vestigation into the nature of Micro-organisms. 



In the very first place, it must be taken into ac- 

 count, that these two elements are represented in ani- 

 mals by a single cell. 



The ovule appears as a minute microscopic sphere 

 enclosed by an envelope (vitelline membrane); it is 

 formed of a mass of granulous protoplasm (vitellus) 

 containing a nucleus (germinative vesicle) and one or 

 many nucleoli (germinative spot). The spermatozoids, 

 in vertebrates, have quite a different aspect: they are 

 filaments of varying lengths, having a distended part, 

 or head, and a tapering, attenuated part, or tail. 



The resemblance that spermatozoids bear to Pro- 

 tista, at first caused them to be regarded as animals 

 living a parasitic life in the spermatic fluid. Ehren- 

 berg classed them among the polygastric Infusoria. 

 Kcelliker and Lallemand were the first to reject this 

 notion and the first to- regard spermatozoids as ele- 

 mental parts of living tissues, having the morpho- 

 logical value of a cellule. They are now likened to de- 

 tached cellular elements, such as blood-globules. 



Whatever form they assume, the sexual elements 

 live as minute organisms independent of the individ- 

 ual from which they originated. This circumstance is 

 particularly remarkable in the case of the male element, 

 the spermatozoid, which retains its vitality for a cer- 

 tain space of time after its expulsion. The length of 

 this period varies with the different species. Whereas 

 the spermatozoids thrown from a trout lose all motion 

 in the water after the expiration of a few seconds, 



