great elevation tends, both directly and indirectly, to induce
inherited modifications in the proportions of the body. (35. Dr.
Wilckens ( Landwirthschaft. Wochenblatt, No. 10, 1869) has lately
published an interesting essay shewing how domestic animals, which live
in mountainous regions, have their frames modified.)
Although man may not have been much modified during the latter stages
of his existence through the increased or decreased use of parts, the
facts now given shew that his liability in this respect has not been
lost; and we positively know that the same law holds good with the
lower animals. Consequently we may infer that when at a remote epoch
the progenitors of man were in a transitional state, and were changing
from quadrupeds into bipeds, natural selection would probably have been
greatly aided by the inherited effects of the increased or diminished
use of the different parts of the body.
ARRESTS OF DEVELOPMENT.
There is a difference between arrested development and arrested growth,
for parts in the former state continue to grow whilst still retaining
their early condition. Various monstrosities come under this head; and
some, as a cleft palate, are known to be occasionally inherited. It
will suffice for our purpose to refer to the arrested brain-development
of microcephalous idiots, as described in Vogt s memoir. (36. Memoire
sur les Microcephales, 1867, pp. 50, 125, 169, 171, 184-198.) Their
skulls are smaller, and the convolutions of the brain are less complex
than in normal men. The frontal sinus, or the projection over the
eye-brows, is largely developed, and the jaws are prognathous to an
effrayant degree; so that these idiots somewhat resemble the lower
types of mankind. Their intelligence, and most of their mental
faculties, are extremely feeble. They cannot acquire the power of
speech, and are wholly incapable of prolonged attention, but are much
given to imitation. They are strong and remarkably active, continually
gambolling and jumping about, and making grimaces. They often ascend
stairs on all-fours; and are curiously fond of climbing up furniture or
trees. We are thus reminded of the delight shewn by almost all boys in
climbing trees; and this again reminds us how lambs and kids,
originally alpine animals, delight to frisk on any hillock, however
small. Idiots also resemble the lower animals in some other respects;
thus several cases are recorded of their carefully smelling every
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