Now let me return to the recent division of biological opinion into two
main streams--Lamarckism and Weismannism Both Lamarckians and
Weismannists, not to mention mankind in general, admit that the better
adapted to its surroundings a living form may be, the more likely it is
to outbreed its compeers. The world at large, again, needs not to be
told that the normal course is not unfrequently deflected through the
fortunes of war; nevertheless, according to Lamarckians and
Erasmus-Darwinians, habitual effort, guided by ever-growing
intelligence--that is to say, by continued increase of power in the
matter of knowing our likes and dislikes--has been so much the main
factor throughout the course of organic development, that the rest,
though not lost sight of, may be allowed to go without saying. According,
on the other hand, to extreme Charles-Darwinians and Weismannists, habit,
effort and intelligence acquired during the experience of any one life
goes for nothing. Not even a little fraction of it endures to the
benefit of offspring. It dies with him in whom it is acquired, and the
heirs of a man's body take no interest therein. To state this doctrine
is to arouse instinctive loathing; it is my fortunate task to maintain
that such a nightmare of waste and death is as baseless as it is
repulsive.
The split in biological opinion occasioned by the deadlock to which
Charles-Darwinism has been reduced, though comparatively recent, widens
rapidly. Ten years ago Lamarck's name was mentioned only as a byword for
extravagance; now, we cannot take up a number of _Nature_ without seeing
how hot the contention is between his followers and those of Weismann.
This must be referred, as I implied earlier, to growing perception that
Mr. Darwin should either have gone farther towards Lamarckism or not so
far. In admitting use and disuse as freely as he did, he gave
Lamarckians leverage for the overthrow of a system based ostensibly on
the accumulation of fortunate accidents. In assigning the lion's share
of development to the accumulation of fortunate accidents, he tempted
fortuitists to try to cut the ground from under Lamarck's feet by denying
that the effects of use and disuse can be inherited at all. When the
public had once got to understand what Lamarck had intended, and wherein
Mr. Charles Darwin had differed from him, it became impossible for
Charles-Darwinians to remain where they were, nor is it easy to see what
course was open to them except to cast about for a theory by which they
could get rid of use and disuse altogether. Weismannism, therefore, is
the inevitable outcome of the straits to which Charles-Darwinians were
reduced through the way in which their leader had halted between two
opinions.
This is why Charles-Darwinians, from Professor Huxley downwards, have
kept the difference between Lamarck's opinions and those of Mr. Darwin so
much in the background. Unwillingness to make this understood is nowhere
manifested more clearly than in Dr. Francis Darwin's life of his father.
In this work Lamarck is sneered at once or twice, and told to go away,
but there is no attempt to state the two cases side by side; from which,
as from not a little else, I conclude that Dr. Francis Darwin has
descended from his father with singularly little modification.
Proceeding to the evidence for the transmissions of acquired habits, I
will quote two recently adduced examples from among the many that have
been credibly attested. The first was contributed to _Nature_ (March 14,
1889) by Professor Marcus M. Hartog, who wrote:--
"A. B. is moderately myopic and very astigmatic in the left eye;
extremely myopic in the right. As the left eye gave such bad images for
near objects, he was compelled in childhood to mask it, and acquired the
habit of leaning his head on his left arm for writing, so as to blind
that eye, or of resting the left temple and eye on the hand, with the
elbow on the table. At the age of fifteen the eyes were equalised by the
use of suitable spectacles, and he soon lost the habit completely and
permanently. He is now the father of two children, a boy and a girl,
whose vision (tested repeatedly and fully) is emmetropic in both eyes, so
that they have not inherited the congenital optical defect of their
father. All the same, they have both of them inherited his early
acquired habit, and need constant watchfulness to prevent their hiding
the left eye when writing, by resting the head on the left forearm or
hand. Imitation is here quite out of the question.
"Considering that every habit involves changes in the proportional
development of the muscular and osseous systems, and hence probably of
the nervous system also, the importance of inherited habits, natural or
acquired, cannot be overlooked in the general theory of inheritance. I
am fully aware that I shall be accused of flat Lamarckism, but a nickname
is not an argument."