H8 THE EVOLUTION OF SEX. 



becomes modified in form, in adaptation to passage through its fluid 

 environment, and the natural result is a flagellate sperm. 



In short, then, the respective morphological characters of the sex- 

 cells, female and male, find the same physiological rationale as do the 

 large passive encysted and smaller active ciliated phases of the cell- 

 cycle in general, and are alike the outcome and expression of predom- 

 inant anabolism and katabolism respectively. Here again we reach 

 the same formula as before; or more cumbrously in words — the 

 functions are either self-maintaining or species-maintaining, individual 

 or reproductive; the former are divided into anabolic and katabolic, 

 the latter into male and female. But the second set of products and 

 processes, so far from being unrelated to the other as is commonly 

 supposed, are in complete parallelism. Femaleness is anabolic pre- 

 ponderance in reproduction, hence the ovum has necessarily the 

 general character which this " diathesis " produces in non-reproductive 

 cells; and, similarly, katabolic preponderance stamps its character of 

 active energy upon spermatozoon as naturally as upon the cilitated 

 cell of the monad. 



Rolph's characterization of the male cells as hungry and starving (katabolic) 

 has been experimentally confirmed by their powerful attraction to highly nutri- 

 tive fluids, and is every day illustrated in their persistent attraction to the ova. 

 Platner has suggested, in the intimately hermaphrodite gland of the snail that 

 the external cells which form the ova are better nourished than the central cells 

 which divide into sperms. Just as an infusorian in dearth of food is known in 

 some cases to divide into many small individuals, so the mother-sperm-cell is 

 perhaps the seat of similar katabolic necessities. The long persistence of vitality 

 seems at first sight a difficulty, if the sperms are highly katabolic cells. It must 

 be noticed, however, (a) that there is often only retention, not continuance of 

 activity, for example, when the sperms lie closely packed in the special storing 

 reservoirs; (b) that the secretions of the female ducts probably afford some nutri- 

 ment to the sperms, which expose an exceptionally large surface in proportion 

 to their mass; and (V) that to a certain extent we may think of them as proto- 

 plasmic explosives, which may remain long inert, but on the presence of the 

 required stimulus are able to start again into extraordinary activity. 



III. The Problem of the Origin of Sex. — We must now 

 return once more to the standpoint of the empirical naturalist, and set 

 out toward the interpretation of sex from a different side — that of its 

 origin. 



It has often been raised as a reproach against the now fortunately 

 dominant school of evolutionist naturalists, that they could give no 

 account of the origin of sex. Some people, like children, wish every- 

 thing at once. Yet it must be admitted that there has been a lack of 

 any sure and certain voice on this question. Apart from the simple 

 fact that evolutionist biology is still young, there are three reasons for 

 the comparative silence in regard to the origin of sex. 



