The sun. [volume] (New York [N.Y.]) 1833-1916, 1892-07-10

species, but that survival IL quito independent
OF the efficiency or nom efficiency OF the organ.
The author OF these essays 10 convinced that
this process OF pnnmixia must have had and
must still have great influence on the devel-
opment Of the organic world. Tho changes
wrought by evolution have been and are In
Vulnerable. and they by no means al
ways occur in an upward direction.
case OF the parasites. in down.
ward ono. or perhaps most frequently In
both directions at once. the change being re-
progressive in ono part and progressive In an
other. Very often. indeed. the former change
may actually lead TO the latter. Civilized mon
could hardly have attained so high degree
OF intellectual development had they not for
feitcd considerable share Of tho physical ad-
yantages possessed by their remote ancestors.
The savage tribes which depend upon the
chase are gifted with much keenor sense OF
hearing. smell. and sight than We arc. and this
10 not m erely the constant result OF training.
but is also due to the inheritance OF
moro efficient organs. In this respect,
according to Prof. weismann. civiliza-
ton has caused degeneration in us by
means Of panmixia, owing to tho fact that the
we'll being OF individuals no longer depends
upon the highest possible development OF
their sense organs. At the present day we
arc able to mako a living equally we'll whether
our sense OF hearing or smell Is delicate or
the reverse. and oven keenness OF sight
is no longer Of decisive Importance to us
In the struggle for existence. Ever since the
invention OF spectacles short-sighted persons
in the higher classes. at any rnte-eIperi-
once hardly any more difficulty in getting
living than that encountered by people with
4, nt.vl,k Tn 10 tp,na chnr ell n nd
soldier or General would have been sheer
impossibiity. and 80 would have been short
sighted hunter. In all grades OF society short
sight used to be serious disadvantage. and.
In truth, an almost complete bar to adj
vancement OF any kind. This Is no longer the
case: a short-sighted man makes his way In
life as successfully as any other. and his de-
feet. II congenital. will be transmitted to his
children. and will therefore tend to mako
hereditary short sight common among GER
tain classes. No doubt short sight may also
DO an acquired character. but In such cases.
according to Prof. Weismann. 1t Is not trans
mitted. His belief Is that the great prevalence
OF short sight is not only due to tho injuries
suffered from over strnininC tho eyes and con-
tinually looking at near objects. but
also to panmixia, or cessation OF the
action OF natural selection-a cessation
to which We are naturally subject In
common with other animals. Much moro
might be said OF the effects Of civilization In
causing physical degeneration. which. indeed.
seems just now to be on the increase among
civilized people. Another example may be
noted in tho teeth: the art Of dentistry has
been brought to such pitch OF perfection that
artificial teeth are now almost to be preferred
to natural ones. 1t Is Mt any rate certain that
no one now need die from insufficient nourish-
mcnt in consequence OF the inability to masti-
cate food. and therefore natural selection will
not interposo to prevent the transmission OF
predisposition to bad teeth to any number OF
descendants
Nevertheless. Prof Weismann docs not foar
that civilization will ever lead to utter degen-
Grafton in man. He sees the antidote in the
very process which causes the first deteriora-
ton of an organ: for obviously such deteriora-
ton can only continue as long as 1t Is not In
furious to the individual in the struggle for
existence. When that point is reached natural
selection will interfere to prevent further de-
generation. 1t is. for instance. pronounced
quite conceivable that the percentage OF per-
sons with hereditary short sight may steadily
increase for a considerable period without ee-
riously affecting tho general standard Of vision
Of mankind as whole. or even that Of a single
nation or class. because degeneration below a
certain point will become q fact OF decisive
importance to tho individual and lead to failure
in the struggle for existence. Thus We need
not fenr the comp lete loss Of our eyes through
degeneration like that which has affected the
animals living In the dark: and we need not
anticipate any serious dimlnution OF our mus
cular strength or powers OF endurance or Of
any other qualities.
II.
In the paber entitled Thoughts Upon the
Musical Sense In Animals and Man." Prof.
Wesmann discusses tho question whether