Initiative in Evolution

by Walter Kidd

[25] p. 17.

[26] Romanes, Examination of Weismannism, p. 115.

“It is doubtful if anything better as to Weismann’s theory of heredity can be said to-day than Romanes said in 1893, and inasmuch as these two latter or distinctive postulates are not needed for Weismann’s theory of heredity, while they are both essential to his theory of evolution, I cannot but regret that he should have thus crippled the former by burdening it with the latter. Hence my object throughout has been to display, as sharply as possible, the contrast that is presented between the brass (“iron” preferably) and the clay in the colossal figure which Weismann has constructed. Hence also my emphatic dissent from his theory of evolution does not prevent me from sincerely appreciating the great value which attaches to his theory of heredity. And although I have not hesitated to say that this theory is, in my opinion, incomplete; that it presents not a few manifest inconsistencies, and even logical contradictions; that the facts on which it is founded have always been facts of general knowledge; that in all its main features it was present to the mind of Darwin, and distinctly formulated by Galton; that in so far as it has been constituted the basis of a more general theory of organic evolution it has proved a failure; such considerations in no way diminish my cordial recognition of the services which its distinguished author has rendered to science by his speculations upon these topics. For not only has he been successful in drawing renewed and much more general attention to the important questions touching the transmissibility of acquired characters, the causes of variation, and so on; but even those parts of his system which have proved untenable are not without such value as temporary scaffoldings present in relation to permanent buildings. Therefore, if I have appeared to play the role of a hostile critic, this has been only an expression of my desire to separate what seems to me the grain of good science from the chaff of bad speculation.”

[27] p. 215.

[28] Heredity, 1908, p. 240.

[29] I prefer to state the above passage rather than that on page 179, which is as follows: “The precise question is this: Can a structural change in the body, induced by some change in use or disuse, or by a change in surrounding influence, affect the germ-cells in such a specific or representative way that the offspring will through its inheritance exhibit, even in a slight degree, the modification which the parent acquired?” (Italics in original). The question is very precise and important, but I employ that given above in preference as lending itself better to the line of inquiry followed here.

[30] The term “character” derives both from its etymological origin and its application to biology a double-edged quality. This is of great value to the study of Mendelism which can only or mainly work with “unit-characters,” and it also serves the Weismann dogma well. In both cases the term obliterates the conception of initial variation, and while serving the purposes of these two great schools of thought it directs attention away from the early minute and unimportant stages by which many germinal variations may have arisen. If it had been coined for the purpose, which it was not, it would have been a remarkable instance of polemic cunning. It will be evident in the course of this study of initial variation, that the accredited and general use of the term “character” begs the question far too manifestly for the general use of biologists. If it be retained for the neo-Darwinian and Mendelian provinces there is nothing to say against it, but I adopt here with pleasure the alternative term, often used by Professor Thomson, “modification.” This is wide enough to include the more clear-cut “character” so long as one makes it clear that the latter is one of the germinal variations. Further, I hold that his use of the term “transmission” instead of “inheritance” is the more useful for a wide range of phenomena. As far as possible I shall employ the expression “transmission of modifications,” instead of that well-worn but often sophisticated expression “inheritance of acquired characters.” This has been subjected by Sir Archdall Reid and Dr. Dixey, to say nothing of others such as Mr. George Sandeman, to a somewhat bewildering analysis. Thus the former says, “It follows that the so-called “acquirements” are innate and “inherited” in precisely the same manner as the so-called inborn characters.”* Dr. Dixey admits “that all characters are both acquired and innate”** and goes on to say that the accepted meaning of the terms was vague, that it led to confusion, and that it ought to be dropped. For this remark of Dr. Dixey one may be thankful, but of my friend Sir Archdall Reid I would ask what he is doing in this galley?

* Nature, Vol. 77, Jan. 30th, 1908, p. 293.

**Nature, Vol. 77, Feb. 1908, p. 392.

Sir E. Ray Lankester in a letter in Nature, 21st March, 1912, dissented from the mode of treatment of this point by Sir Archdall Reid and presumably also by Dr. Dixey in the words “It is not, I think, permissible to say that the normal characters which arise in response to normal conditions are with equal fitness to be described as ‘acquired.’” As to what is a normal character and what are normal conditions there may be much reason for difference of opinion, but I have said enough of this discussion to show that the terms “acquired” and “character” would afford a biological Pascal some such food for criticism as did the term “probable” in his Provincial Letters. The less these two terms are employed the less misunderstanding there will be of certain problems.