ioi6 LIFE : OUTLINES OF GENERAL BIOLOGY 



throughout their main development also? Since their development, 

 maturation, and decline so markedly determine the main phases 

 of development of the body, must not the body's growth and 

 development in some measure affect them in turn? The gonads which 

 produce these cells contribute important hormones to the body, and 

 towards its phasal changes; and the body's hormones in its circula- 

 tion cannot but in some measure reach these ; so why not influence 

 them too? And as the importance of neural and psychic tone is 

 appreciated throughout the physiology of health and disease alike, 

 and by all schools of medicine however otherwise differing, since of 

 the very maintenance as well as recover}^ of health, can gonads and 

 germ-cells be conceived as lying wholly outside such influences? 

 And since each germ-cell carries with it the psychic heredity of its 

 species, continued from that of its real parents of the previous 

 generation, can it be whoUy insensible to the psychic states, as 

 affecting neural tonus of the body which has so long nourished and 

 borne it ? Since its maturation and emergence to fertilisation raises 

 the bodily and even the psychic life to ever-increasing intensities, 

 even to orgasms in which culminate the ecstasies and agonies of 

 life, can it be wholly independent and unmodifiable, and at what is 

 also its own life-crisis? Important though be our anatomic and 

 histologic knowledge, may not love's unions have more in them than 

 we know? And in the strangely mingled and glowing witchpot of 

 each individual life, how can its germs escape being deeply dyed? 



We cannot as yet answer any of these questions — which would 

 involve subtleties of research beyond all ordinary ones : yet they are 

 suggested as tending to keep open outlooks and towards possibilities 

 which various elements of the very progress of knowledge which we 

 have been appreciating have sometimes been too apt to close. 



NATURAL SELECTION OR NATURE'S SIFTING 



A strange irresponsibility of judgment among naturalists is 

 indicated by the frequent swing of the pendulum away from the 

 Darwinian theory of natural selection as a vera causa in organic 

 evolution. Because we are beginning to know a little more about 

 the raw materials of evolution — the germinal changes that find 

 expression as bodily fluctuations and mutations — must we leap to 

 the conclusion that there is no need for natural selection ? Because 

 we have a little more light than Darwin had on the originative 

 factors in organic evolution, must we swing to the exaggerated 

 view that directive factors or eliminating factors do not exist or 

 do not count ? 



No one has contributed more than Hugo de Vries to our knowledge 

 of variations, and no one has more firmly indicated the limitations 



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