Some Problems of Reproduction: a Comparative Study of ...

SOME PEOBLEMS OF REPRODUCTION. 73
and delicate sensibility j 1 and by this differentiation of temperament
the zygote would be the gainer. This I take to be the
ORIGIN 01? SEX. Once started in some such way, the difference
of temperament between the gametes would tend to be more and
more accentuated and, so to say, crystallised; and this would be
as it were anticipated, first in the organs and then in the individuals
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 indications
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 difficulty
in understanding the continuance and hardiness of many
self-impregnating flowers, and of that sturdy group of selffertilising
animals, the parasitic Flat worms. 2
E. PARAGENETIC PROCESSES, USUALLY COMPRISED UNDER THE
TERM " PARTHENOGENESIS."
By PARACSENESIS 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 sensibility
to chemical stimuli.
1 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 togetlier
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.