SPECIFIC CENTRES. 



13 



The adaptation of species to the conditions in wliicli they arc to jiass tlicir lives, as of tree 

 kangaroos to a life in trees, or blind animals to a life in darkness, is, I think, a phenomenon of a 

 different nature, and regulated by other laws, the working or nature of which does not come within 

 the scope of this inquiry. I offer no opinion here ujwn that subject. Only of one thing I may 

 say, I feel as sure as I can be of anj'thing which I do not know, and that is, that it is not b}' 

 the process supposed by Mr. Darwin, viz., by Nature trying an infinity' of experiments and rejecting 

 them all until she hit upon the right one. Nature never makes chips. When the occasion for 

 a tree kangaroo arose, M'c may be sure that the tree kangaroo appeared perfect at the first attempt. 

 There was no failure of myriads of forms of kangaroos in other directions created or developed 

 but to die, until by chance one in this direction appeared. Tltai I feci, but I cannot prove it ; 

 it is only my feeling, and therefore of no vise to any one but myself. 



Of course, in adopting the view which I have above explained, I abandon, to a certain extent, 

 the theory of specific centres of creation ; and I adopt, to a like extent, the theory of a multiple 

 origin of species. But neither unconditionally. I abandon the idea of specific centres of creation only 

 so far as that implies that the original centre was confined to one or two single progenitors. My 

 centre is the whole si^ccies ; — from the region where it received the impress of its character, it may 

 sjjread in all directions, continuing unchanged wherever it feels no important change in its con- 

 ditions of life ; becoming changed into another species or variety when a change on them makes 

 itself felt. In like manner mj' multiple origin of species is not that of Agassiz, who imagined 

 the same 8j)ccies to be produced separately and independently of each other in many different 

 places without communication, as, for example, the same species of fish to be produced in three 

 different rivers between which there were no means of communication.* 



* I hope that I have correctly interpreted Agassiz's 

 views ; I have taken them from the following quotation 

 from his paper on the subject in the " Edinburgh 

 New Philosophical Journal:" 



"Let us compare tlie different species which occur in 

 the Danube, in the Rhine, and the Rhone, three hydro- 

 graphic basins entirely unconnected with each other 

 throughout their wliolo extent. They spring from the 

 same mountain chain, as we may take the Inn as the 

 source of the Danube. These three great rivers take 

 their rise within a few miles of each other. Nevertheless, 

 most of their fishes differ ; but there are some which are 

 common to the three. * • * if the.se animals had not 

 originated in these rivers sepai'ately, why should not sucli 

 closely-allied species — some of which occur in the three 

 basins^ — have all spread equally into them ; and if they 

 originated in the separate basins, we have, within close 

 limits, a midtiple origin of the same species ; and that this 

 multiple origin must be admitted as a fact, is shown by 

 the following further evidence. Among the carps we find, 

 for instance, Barbus, Gobio, Carpio, common to the three ; 

 but the Danube has three Gobios, whilst the others have 

 but one — one of the Danube being identical with the one 

 of the other two rivers. The mo.st striking fact, however, 

 occurs in the genus Leuclscus. L. L'ODULA is common to 

 the tlu'ee ; but in addition to it the Danube has second 



species, which occur neither in the Danube nor in the 

 Rliine ; and in the Rhine there are species which be- 

 long neither to the Rhone nor to the Danube. Now 

 we ask, could all these species of Leuciscos have been 

 created in one of the basins in the Danube, for instance, 

 and have migrated in such a way that a certain number 

 of the species should remain solely in the Danube, 

 while some others left the Danube altogether to settle 

 finally only in the Rhone, and others to settle only in the 

 Rhine ; that one accompanying those species jjeculiar to 

 the Rhone remained in the Danube with those species 

 peculiar to it, and settled also in the Rhine with those 

 species peculiar to that river ; and also in the Rhino, with 

 the species peculiar to the Rhine. And whether we assume 

 the Rhone as the primitive centre, instead of the Dauvibe 

 or the Rhine, the argument holds equally good. We have 

 one species common to the three rivers, and several spe- 

 cies peculiar to each which could never have migrated (if 

 migration took place) in such a manner as to assume this 

 present combination. But if, on the contrary, we suppose 

 that all the species originated in the rivers where they 

 occur, then we have again a multiple origin of that species 

 which is common to the three, for it were wonderful if 

 that one alone had migrated when they were all so closely 

 allied." — Ag.vssiz, iu " Edin. New Phil. Journ." vol. xlix. 

 p. 12. 



