Sept. 30, 1875J 



NATURE 



479 



DOHRN ON THE ORIGIN OF THE VERTE- 

 BRA TA AND ON THE PRINCIPLE OF SUC- 

 CESSION OF FUNCTIONS 



'T'HE introduction of the doctrine of Descent into the 

 ■■■ study of organic phenomena has opened the flood- 

 gates of speculation, of hypothesis, and theory. Pro- 

 bably, with very few exceptions, this is regarded with 

 regret and impatience by zoologists and botanists, even 

 though staunch Darwinian converts, who had made any 

 name in biology in the period anterior to the publication 

 of Mr. Darwin's work on the " Origin of Species." Those 

 were the days of a reaction brought about by the fan- 

 tastic imaginings of Oken and his school ; and the natu- 

 ralists brought up in those days cannot rid themselves of 

 a dread of speculation which has become as much an 

 organic part of their nervous systems as has the fear of 

 precipices, bricklayers' ladders, and of the mythological 

 personages of their childhood, to most men. It remains 

 for the present and later generations who will be brought 

 up, not to fear, but to use speculation, to turn fully to 

 account the immense engine of research which Mr. 

 Darwin has placed in their hands. We see, in fact, no 

 reason for refusing to welcome any number of hypotheses 

 and theories on biological topics : let every one make his 

 suggestion— the more ingenious and original the better — 

 and let it be taken for what it is worth. If in its author's 

 or another naturalist's hands it should lead to the dis- 

 covery of new facts — if it should in a more or less modi- 

 fied form be established as true — it will bring thanks and 

 honour to its promoter. If, on the other hand, it should 

 lead to nothing, should be tested and found neither true 

 nor suggestive of truth, it will fall to the ground quietly 

 enough, and do no harm to anybody. This, be it said, 

 applies only to the pubhcation of such hypotheses within 

 the scientific area — a totally different and a very grave 

 responsibility is incurred when an author represents a 

 hypothesis as an established doctrine, and appeals to the 

 support of an uninstructed public. The fact is that we 

 have acquired this freedom of speculation as compared 

 with the proscription of it in the pre-Darwinian period, 

 through the circumstance that biological theory has 

 passed from the theological to the scientific form. To- 

 day — no matter who its author — a speculation as to the 

 mode of development of this or that group of animals and 

 the significance of this or that organ, may be verified or 

 rejected ; no one will attach undue value to it until this 

 process has been gone through. Formerly it was not 

 possible to test such speculations ; we had in fact no hnk 

 by which organic phenomena were made part of the 

 whole series of phenomena of which science takes cog- 

 nisance, and biology had no foundation in the so-called 

 experimental sciences. Hence speculations were liable 

 (as in theological discussion) to be launched by authori- 

 ties, and to be received not as speculation, but as something 

 like inspiration, by disciples ; and on the other hand to 

 be rigorously and almost puritanically tabooed by a con- 

 stantly increasing number who, refusing to occupy them- 

 selves with these vain imaginings, endeavoured to keep 

 the facts pure and undefiled, waiting for the coming 

 of an interpreter — who was realised in Mr. Darwin. 

 The doctrine of organic evolution as elaborated by Mr. 

 Darwin and his immediate successors has provided us 

 with a proper scientific framework, and we can now 

 proceed to build on that by the legitimate methods of 

 modern inductive science. It will be some time before 

 biology fully emerges from its theological form ; at least 

 another generation must pass ; and in the mean time we 

 must expect the continuation of special claims on the 

 part of authorities to advance speculative doctrines ex 

 catJied?-d ; and on the other hand a hngering antagonism 

 to all speculation, even to that which makes no pretension 

 to authority, on the part of those who have imbibed the 



horror of fantastic "^Natur-philosophie " and of dogmatic 

 pretensions. 



To those who belong to neither of these 'sections, it is 

 worth while pointing out that even the most careful 

 observation and recording of phenomena in the absence 

 from the observer's mind of some theory or speculation 

 which shall, so to say, sharpen his wits and keep his 

 eyes open, is likely to be of the very smallest value. It 

 cannot be too strongly asserted that in observing a com- 

 plicated phenomenon — such as an organic structure or 

 series of structures — the investigator is only likely to see 

 what he has already imagined inay be there ; the chances 

 are greatly against his detecting an arrangement or a 

 mode of development of which he had previously no 

 suspicion. Though cases of unforeseen discovery do 

 occur, yet it may be safely stated that, as far as all but the 

 most patent and macroscopic appearances are concerned, 

 the observations of no predecessor should be trusted by 

 an investigator beyond the limit which is given by the 

 hypotheses which are known to have been present to that 

 predecessor's mind. In fact, a man can only expect to get 

 answers from Nature to specific questions ; she will not 

 give him unsolicited information, nor make a voluntary 

 statement, however attentive the listener. Hence the 

 value and legitimacy of speculations, even ad nauseam, 

 on such matters as the pedigree of animals and plants. 

 When advanced, with due knowledge of ascertained facts, 

 they suggest to the embryologist, to the paleontologist, 

 and the anatomist, a number of possibilities which he 

 holds before him as so many questions to be answered by 

 the material of his studies. It is true that it is desirable 

 in a high degree that the person who frames a hypothesis 

 should also himself be active in using it in a practical 

 way, and indeed if he is not, he may find no one who 

 will take the trouble to bear it in mind. Therefore, one 

 must admit the generosity of those who now-a-days make 

 a present of their speculations to scientific confreres, and 

 undertake the part of the profound thinker, whilst assign- 

 \r\3; to others the more practical task of verification and 

 elaboration. For, since the days of scientific inspiration 

 are past, but little credit will attach to the launchers of 

 hypotheses, and more and more to those who destroy 

 them, either by showing their error or by transubstantiat- 

 ing them, in demonstrating that which was supposed, 

 actually to be. It is Darwin whose name we associate 

 with the doctrine of evolution — not Lamarck's, nor 

 Goethe's, nor Wells', nor Freke's. 



These remarks are a necessary prelude to the consi- 

 deration of the bold speculations with which Dr. Anton 

 Dohrn, the founder of the zoological station of Naples, 

 known also for some interesting observations on the 

 development of Crustacea, has recently astonished the 

 zoological world in his " Ursprung der Wirbelthiere und 

 Princip des Functionswechsels." The necessary sequence 

 of the general acceptance of Darwin's theory of the origin 

 of species by descent and natural selection has been an 

 attempt to establish the pedigree of the animal kingdom, 

 and to indicate the degrees of consanguinity among 

 the different members of it known to us. In the 

 first attempts in this direction no one can doubt that 

 errors and vagaries of all kinds must occur. It is 

 only when naturalists have fairly set themselves to the 

 task and made some few false starts that we can expect 

 to see anything like a just appreciation of the methods to 

 be pursued, of the difficulties to be encountered, and of 

 the fallacies to be avoided. We are obliged to admit 

 that the first attempts in the way of constructing the 

 pedigree have been influenced, as they were likely to be, 

 by the remnants of old notions and by the lack of a per- 

 fectly unprejudiced appreciation of the question in hand. 

 The pamphlet of Dr. Dohrn comes opportunely enough 

 to insist upon one or two important considerations which 

 have been neglected ; and *ven though, by an excess of 

 antagonism to prevailing prejudice, Dr. Dohrn may be 



