SOME PROBLEMS OF REPRODUCTION. 73 
and delicate sensibility ;1 and by this differentiation of tempera- 
ment the zygote would be the gainer. This I take to be the 
OriGIn or Sex. Once started in some such way, the difference 
of temperament between the gametes would tend to be more and 
more acceutuated and, so to say, crystallised ; and this would be 
as it were anticipated, first in the organs and then in the indi- 
viduals producing the gametes. I accept then one main thesis of 
the ‘‘ Evolution of Sex,” that male and female are distinguished 
by their respective temperaments ; though it is obvious that I 
reject utterly its theory of sexual karyogamy that the male 
brings “ katastates,” the female “ anastates,’ which combine 
to make the zygote a perfect organism equipped for any event. 
I have stated that I consider the difference of temperament 
to be the advantage brought by bisexuality ; and in allogamic 
bisexuality this advantage is doubled: hence the many indica- 
tions on which has been based the old adage that ‘ nature 
abhors perpetual self-fertilisation.”” But, on the other hand, 
if we admit that allogamy is, like karyogamy itself, a mere 
“ acquired need ”’ or “‘ necessary superfluity,” we have no dif- 
ficulty in understanding the continuance and hardiness of many 
self-impregnating flowers, and of that sturdy group of self- 
fertilising animals, the parasitic Flat- worms.’ 
E. ParaGENETIC PROCESSES, USUALLY COMPRISED UNDER THE 
TERM ‘¢ PARTHENOGENESIS.” 
By Paracenests I designate all modes of reproduction in 
which a body, not the zygote, simulates the behaviour of the 
1 The way many Arthropods find their mates by smell is well known; 
spermatozoa of plants find the oosphere owing to their very delicate sensi- 
bility to chemical stimuli. 
2 The variation in individual susceptibility to harm from close breeding is 
extreme. The human race is usually believed to suffer greatly from close 
breeding; and yet some of its hardiest and finest specimens are the members 
of fishing communities, isolated by position or by custom, and bound together 
by the closest and most complex ties of blood. Similar facts as regards the 
vigour of cleistogamous and other self-pollinating types of plants have led to 
many attacks on the adage cited above, made notably by A. W. Bennett, G. 
Henslow, Neehan, &c. 
