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affirms it with singular conclusiveness, because he is repudiating there the representation that had been made by his critics to the contrary effect. In the preface to the second edition of "The Descent of Man" he says:—
I may take this opportunity of remarking that my critics frequently assume that I attribute all changes of corporeal structure and mental power exclusively to the natural selection of such variations as are often called spontaneous; whereas, even in the first edition of "The Origin of Species," I distinctly stated that great weight must be attributed to the inherited effects of use and disuse with respect both to the body and mind.
If natural selection stopped short at putting stress upon organisms, even the forms most susceptible of correlated change might not be capable of resisting death. But, assuming within an exterior change at least temporary endurance of the new conditions, no organism, without use and disuse of existing parts, could rise or fall, in function or structure, above or below the forms best adapted to survive at the time of the changed conditions. The fittest at that time, if they survived, would remain through their descendants, if the exterior conditions did not again change, the fittest for all time to survive. There would be no evolution, that is, no development to higher or lower forms their status would be permanently fixed. An aquatic anima! could not have become a terrestrial one, nor a terrestrial one, as in the case of the placental mammal, the whale, an aquatic one.
Nature can modify nothing to the extent of making it a new creation merely by putting stress upon it. Stress is more than negative it represents opposition where it does not represent antagonism. Opposition does not of itself create by the slowest, or any, process. Only, as from the effects of use and disuse of parts in changing function and structure, is it possible to conceive of organisms subjected to change in environment continuing to live with different aspects under changed conditions.
We have already remarked of the second learned gentleman's
contention, that only congenital characters are inherited because acquired characters are not inheritable, that it is a begging of the question whether acquired characters do or do not become congenital. As, however, his dictum comes within the lines of what a much more prominent man, August Weismann, thinks, we will examine some of the points made by the latter in his work," Essays upon Heredity and Kindred Biological Problems." We quote from the late English translation of Weismann's work (page 85) as follows:
When the wild duck became domesticated and lived in a farm-yard, all the individuals were compelled to walk and stand more than they had done previously, and the muscles of the leg were used to a correspondingly greater degree. The same thing happens in the wild state when any change in the conditions of life compels an organ to be more largely used. No individual will be able to avoid this extra use, and each will endeavor to accommodate itself to the new conditions according to its power. The amount of this power depends upon the predisposition of the germ, and natural selection, while it apparently decides between individuals of various degrees of strength, is, in truth, operating upon the stronger and weaker germs.
This statement, whether or not Weismann saw the absurd consequence, means that the prepotential force of the original germinative plasm so overrides every other tendency of the wild duck that the germ must contain in itself special reference to the duck's becoming pedestrian in a wild state, or as belonging to a farm-yard breed.
Weismann says, on page 189 of the translation mentioned :
E. Roth has objected that in pathology we everywhere meet with the fact that acquired local disease may be transmitted to the offspring as a predisposition; but all such cases are exposed to the serious criticism that the very point that first needs to be placed on a secure footing is incapable of proof, viz., the hypothesis that the causes which in each particular case led to the predisposition were really acquired.
What is the question? It is whether or not disease can be inherited. Weismann says that it cannot be, unless the predisposition, as having been acquired, can be demonstrated. This slams the door in the face of the anxious inquirer after truth, for, no matter how many or few generations in a line of descent
one might go back to find a point when the predisposition had been acquired, the answer would be, despite all circumstantial evidence proving the fact of such acquirement, How do you positively know that it was then acquired? Weismann's position in this denial is a very safe one, for it renders, so far as he is concerned, all prospect of a solution of the question impossible, through evasion of the conclusions that are deemed legitimate from recognized, premises in similar investigations. Primeval perpetuity, according to his statement, must be allowed to predisposition, and its ever being an acquired character may, therefore, be safely denied. According to this dictum, the first man must have had a disease badly to have been able to transmit it so far.
On page 269 of the translation, Weismann out-herods Herod in this kind of argumentation, when stating that—
The children of accomplished pianists do not inherit the art of playing the piano; they have to learn it in the same laborious manner as that by which their parents acquired it; they do not inherit anything except that which their parents possessed when children, viz., manual dexterity and a good ear.
Did any one ever claim that it is necessary to the doctrine of hereditability of acquired characters that such a possession as this should be proved to have been transmitted? This is not an acquired character,-it is not a character at all; it is an acquired art. Weismann might as well have said that we do not observe that the children of famous pianists are born with a piano. He goes on to say in the same passage:
Furthermore, language is not transmitted to our children, although it has been practiced not only by ourselves, but by an almost endless line of ancestors.
Why, is it not known on all sides that articulation, without reference to language, is but a faculty only secondarily combined with organs whose primary function is for an entirely different purpose, and that speech, as the existence of different languages proves, is only a conventional mode of communicating thought,
and constitutes merely an art? Who ever thought of claiming that any art-music, speech, painting, or sculpture, or aught else that is extrinsic to the body-could be affected by heredity? Such arguments as these make one lose all confidence in the conclusions of Weismann's personal microscopical investigations, in which otherwise one would gladly look for instruction.
With one more citation from this work on heredity, we conclude the presentation of what we deem sufficient evidence to prove the utter unreliability of Weismann's conclusions. It is to be found on pages 95 and 96 of the work hitherto quoted from :
In my opinion, there is absolutely no trustworthy proof that talents have been improved by their exercise through the course of a long series of generations. The Bach family shows that musical talent, and the Bernoulli family that mathematical power, can be transmitted from generation to generation, but this teaches us othing as to the origin of such talents. In both families the high-water mark of talent lies not at the end of the series of generations, as it should do if the results of the practice are transmitted, but in the middle.
This proves nothing but that the intermixture of other blood, not specially endowed in the same direction, diminishes mental manifestation of the original talent. It has been proved repeatedly by Galton and others that descent in the direct line, despite this intermixture, has long shown hereditary qualities of marked type, generation after generation of persons peculiarly adapted to certain employments being engaged in them in numbers so great that it is impossible to suppose that those employments were originally sought by all on account of their special personal aptitude for them. If the increased speed of the trotting horse within fifty years, from a mile in two-forty to about a mile in two-ten, is not significant of change in the animal, due to appropriate change in function and structure, in addition to the effects of artificial selection of stock to breed from, what else will account for it? The gait, as a fast one, is not natural to the horse; the extreme development of what the
best horse could at first do with practice in the trot was soon reached; artificial selection could find nothing better than was at first discovered in the way of stock to breed from. Whence, then, can come what still remains to be accounted for in the enormous increase, in fifty years, of speed in the trotter, but from its having been modified in function and structure, and the effects transmitted to the progeny? If men and women did not mate for love and money and a thousand other motives than with reference to the qualities of their descendants, but, like the domesticated animals, were bred for various qualities, we could make great musicians, painters, mathematicians, generals, or athletes, at pleasure, unchecked save by the occasional effect of atavism. Although this will never be, we may yet clearly perceive, if we but observe closely, with minds divested of prejudice, the working of the indicated law, which, as it has ever done, holds important sway at all times and in all places on earth.