24 JOURNAL AND PROCEEDINGS 



solitary form on the face of the globe to-day identical in every par- 

 ticular with that in which it originated — not even man himself — all 

 having been more or less subjected to the modifying influences of 

 external conditions. This being the case, we have no means of 

 knowing with certainty what any species may have been like when 

 first originated ; nor can we tell what kind of change would take 

 place in an organism by a given change in its surroundings, that, as 

 yet, is only known by observation, for we do not know what is the 

 geologic and climatic chemical compound that constitutes the in- 

 fluence of any locality of the present, and far less of the past. So 

 that if we would trace any species from its origin to the present, we 

 must deal with the principles that are at work, and leave the form 

 to the imagination. For a time, then, let us go back in thought 

 to the first appearance of a pair of some species, on a continent with 

 diverse geographical conditions. That pair would, no doubt, be in 

 perfect harmony with its environment, in size, form, color and con- 

 stitution ; they would propagate and multiply, and in due time the 

 progeny would fill the locality, then overflow into other localities, 

 there in turn to repeat the process, and pass on until the continent 

 was completely stocked with that species ; but in their migrations 

 they have come in contact with geographical conditions quite differ- 

 ent from those they had left, which would act upon them and change 

 their appearance more ro less, to bring them into harmony with 

 their new conditions, so that we would have not only the land filled 

 with the species, but we would have a number of local varieties of 

 that species, each adapted to its own locality. Now as it is a mi- 

 gratory species we are considering, some of those varieties would in 

 time return and get into localities already occupied by a different 

 one, then crossbreeding would begin, with such consequences as we 

 have already seen, when we would be likely to get several forms of 

 the same species in the one locality, and some of these might be 

 quite different from any of those that had hitherto appeared. I 

 would just note here the principle of reversion, and the likelihood 

 of permanent residence bringing a migrant into conformity with the 

 native, more or less exact. Now suppose that this species had the 

 power, or opportunity of getting to another continent, and continue 

 its progress until it had encircled the globe, it would meet with more 

 diversity of conditions to be yet more changed thereby. Then sup- 

 pose some violent commotion took place, separating some portions 



