39.2 Mr. S. V. Wood on the Effects upon Animal Life 



adapted to the conditions of habitat, and especially created with 

 reference to the conditions nnder which it was to exist. We see 

 the latter hypothesis fail when tested by the effect which the 

 introduction of domestic animals, and of some of the wild ones 

 which follow man in his migrations, has had in these regions — 

 an effect so nnmistakeable, that we cannot doubt but that the 

 later introductions will eventually exterminate the indigenous 

 population, and would have done so ages ago had the geogra- 

 phical conditions permitted the migration of the animals of the 

 Europeo-Asiatic continent into these sequestered portions of an 

 earlier land. 



The preservation of the fauna of past geological periods in a 

 state of isolation more or less complete has not, so far as I am 

 aware, yet received much notice from geologists, doubtless from 

 the reluctance hitherto exhibited by them to argue from any 

 premises which involved the admission that all animated beings 

 originated from common parents; but we now appear to be 

 on the eve of a change in this sentiment, and of an admission 

 that every organism has originated by parturition from one pre- 

 existing, and not by creation out of an inorganic matrix, and that 

 the organic world resembles an ever-branching tree, in which the 

 orders, classes, subkingdoms, and even the animal and vegetable 

 kingdoms themselves, are respectively connected by the lower or 

 simpler types of each, rather than a chain or succession of types 

 in which the lower grades of one group have originated out of 

 the highest grades of that usually placed next below it. We 

 may therefore look for less reluctance among geologists to ap- 

 proach a subject which is by no means confined to the more con- 

 spicuous examples which I have here sought to bring into notice. 

 The preponderance of the orders Bruta and Edentata on the 

 American continent, and the existence of the latter order in Africa 

 and India, will, I think, one day be attributed to the isolation of 

 portions of very ancient land in those places, from an epoch 

 when those simpler forms of mammalia constituted the highest 

 stage to which the animal kingdom had attained, and to the sub- 

 sequent incorporation of those parts with newer land containing 

 more advanced forms, permitting the reciprocal migration of 

 their inhabitants. The preservation on various parts of the earth 

 remote from each other of animals of kindred structure, limited 

 now to almost a single species, and unfavourable to migration, 

 such as the Proteus and Lepidosiren, or the few surviving forms 

 of the Salamander, points also, in my mind, to a somewhat similar 

 process commencing at a much more remote date, when the cha- 

 racteristics of these solitary survivors were those of the highest 

 grades to which life had then attained, — a process, however, 

 which has been modified by many subsequent occurrences, that 



