274 THE EVOLUTION OF SEX. 



even mainly, as an intellectual construction, but as a discipline of life; 

 and we need more. We need an increasing education and civism of 

 women, — in fact, an economic of the sexes very different from that 

 nowadays so common, which, while attacking the old cooperation of 

 men and women because of its manifest imperfections, only offers us 

 an unlimited and far more mutually destructive industrial competition 

 between them instead. The practical problems of reproduction become 

 in fact, to a large extent, those of improved function and evolved 

 environment; and limitation of population, just as we are beginning to 

 see the cure of the more individual forms of intemperance, is primarily 

 to be reached, not solely by individual restraint, but by a not merely 

 isolated and individual, but aggregate and social, reorganization of life, 

 work, and surroundings. And while our biological studies of course 

 for the most part only point the way toward deeper social ones, they 

 afford also one luminous principle toward their prosecution, — that 

 thorough parallelism and coincidence of psychical and material consid- 

 erations, upon which moralist and economist have been too much wont 

 respectively to specialize. 



VI. Rate of Reproduction " Nil." — Sterility. — When we view 

 reproduction in terms of discontinuous growth, — that is, as a phenom- 

 enon of disintegration, — it is obvious that complete integration of the 

 matter acquired by the organism into its bulk, and for its own devel- 

 opment, precludes reprodnction, — that is, involves sterility, — and 

 similarly as regards the energies of the organism. This is only a 

 restatement of Spencer's generalization above discussed; for it is 

 evident that, if genesis vary inversely as individuation, it must be 

 suppressed altogether if individuation becomes complete. The actual 

 phenomena, however, by no means usually admit of explanation as 

 such realizations of the ideal of evolution, and hence the cause and 

 treatment of sterility mainly pass into the provinces of the experimental 

 naturalist and the physiological physician. From the earliest times, 

 indeed, physician and naturalist, priest and legislator, alike devoted 

 attention to the subject; and it was probably in this way, as a recent 

 monographer remarks, that research became directed to the larger 

 problem of reproduction in general. The general biological questions 

 — for example, the relations between sterility within the limits of a 

 species to changes in the environment, or that of sterility among 

 hybrids — are extensively discussed in the copious literature which 

 centers around Darwin's Variation of Animals and Plants under 

 Domestication ; while with regard to the human species, an extensive 

 medical literature of course exists, to which any encyclopedia of med- 

 icine, or conveniently the recent monograph of P. Miiller {Die 

 Unfmchtbarkcit der Ehe, Stuttgart, 1885) will furnish bibliographical 

 details. 



