, 1876-07-29

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but in our farm yard breeds the latter
sometimes become developed and yield
milk. In like manner the atrophicd
tcats in male domrStcltcd animals, in
GLIDING man. have occasionally grown to
full size, and scCrctcd milk
In some organisms, when one part
varies, certain other parts always, or
nearly always, vary simultaneously.
They are then said to obey the law of
correlated variation. 1t should follow
that when one part Is modified through
long continued selection, either 10y man
or under nature, other parts OF the or
gnni2tiOn will lr unnvOidably altered !;
and it is fact that with our dOmcSti-
Gated plants and animals, varieties rarely
or never differ by single character
alone. If the beak of birds, for instance,
increases or decreases in length, adjoin-
ing or correlated parts, as the tongue
and the uriticG of the nostrils, tend To
vary in the same manner. llomologous
parts which are identical in the embryo,
and are exposed 20 similar conditions,
deyiatc in the same or in some connected
way, as with the right and lett sides of
the body, or with the front and hind
limbs. The skin and the appendagcs OF
hair, feathers, hoots, horns, ana teeth,
nrc hOmologous over the whole body.
Accordingly several tropical Breeds Of
sheep, which are clothed with hair in
stead Of wool, have horns very like those
Of goat. With men, striking instances
have been recorded OF inherited badness
coupled with hereditary deficiency,
either complete or partial, of the teeth.
Darwin cites the case of a llindoo tami-
", of which ten males in the course of
four generations were furnished in both
jaws taken together with only four weak
incisors and eight nolars the same men
had very little hair nn the body, and be.
came bald early in life. 1T is remark.
able" he adds, "that no instance has DC.
cured in that family 0f n daughter SIM
iarly affected, and this fact reminds US
how much more liable men are in Eng.
land to become bald than women" In
this category belongs the case Of Julia
Pastrana, q Spanish dancer, who had II
thick masculine beard and u hairy fore
head, and, correlated with these peculi-
arities, full double set Of teeth in each
jaw, ono row being placed within the
other. it seems further TO be admitted
that the organs Of sight and hearing are
homologous with one. another Thus
color blindness is often associated with
corresponding inability to distinguish
musical sounds. White cats, if they
have blue eyes, are almost always deaf.
Here the cause Is supposed to lie in q
slight arrest Of development in the nerv-
Gus system connected with the sense
organs at The stage Of the closed eyelids,
as the iris in kittens during that period
has been found to be of blue color.
Finally, there is some authority for the
old belief that in man (as certainly in
animals) there is q conne,tion between
complexion and constitution. It has
been shown, tor instance, that relation
exists between liability TO consumption
and the color OF the eyes, hair, and skin.
It is even affirmed that in the French
army which invaded Russia, soldiers
having dark complexion, from the
southern parts Of Europe, withstood the
intense cold better than those with
lighter compilations from the north. As
to pigs and sheep, there is no doubt that
the white sorts are poisoned by various
plants which prove innocuous to the
black species. With cattle, indcpend-
emily of the action of any poison, cases
have been published of cutaueOus dis
eases affecting every single point which
bore white hair but completely passing
over other parts of the body. White
terriers suffer most from the distemper,
and white chickens from the gapes.
Analogous facts have been observed
with plants. White onions and verbenas
are the most liable to Inildew, and in
Spain the pale frui,ed grapes suffer most
from the vine disease. Red wheats
likewise are harder than white. All
this would indicate that some grave con.