456 Canadian Record of Science. 



did honestly endeavour to distinguish, between mere suc- 

 cession of forms, among which there might be no genetic 

 bond, and those which show at least a probability of such 

 connection. The difficulties in securing such facts he 

 frankly stated ; and if. for example, he held it probable 

 that the horse had been derived from an animal of the 

 type of Hipparion of the middle tertiary, he kne'w that 

 this required, not merely the successive changes in foot 

 and tooth, but a vast variety of correlated changes, and 

 these occurring under varied geographical and climatal 

 conditions, and movements of migration, accompanied 

 with partial extinctions, isolations and intermixtures, 

 none of which are certainly known to us in their detail, 

 and the greater part have to be imagined. Of these points 

 he gives intimations in his discourse of 1870 on Palaeon- 

 tology and Evolution, reprinted under his own supervision 

 as late as last year. In face of all this, it is obvious that 

 the doctrine of natural selection becomes quite insig- 

 nificant as a factor in evolution, or is mixed with so many 

 questions as yet unsolved that the problem becomes in- 

 tensely complex. Small minds can easily cut this knot, 

 but Huxley strove to untie it, and that without the help 

 he might have derived from the belief in a pre-determined 

 plan of development. 



Tracing back the evolutionary history of animals, he 

 further finds that he can by no means reach its beginning. 

 As he puts it, " If there is any truth in the doctrine of 

 Evolution, every class must be vastly older than the first 

 record of its appearance upon the surface of the globe. 

 But if considerations of this kind compel us to place the 

 origin of vertebrated animals at a period sufficiently dis- 

 tant from the silurian in which the first elasmo-branchii 

 and ganoids 1 occur, to allow of the evolution of such 

 fishes from a vertebrate as simple as the Amphioxus, I 

 can only repeat that it is appalling to speculate upon the 



l Sharks ami bony pikes. 



