THE HAMILTON ASSOCIATION. I 7 



highest — men not excepted — are produced through eggs, says : " It 

 is a marvellous process, that of the inner life of the yolk, leading to 

 a result so extraordinary as the formation of a new living being. 

 Here is something wonderful ; not only the simplicity of the process 

 by which the change is brought about, but still more marvellous is 

 the fact that all this goes on from within. There is a principle act- 

 ing by the aid of the substance which holds it, never deviating from 

 its course, and always leading to the production of a being like 

 the parent." 



Now it is clear that if this principle or law of nature was always 

 acting unopposed, there would be no difficulty in deciding (by 

 structure) to what Species any form belonged, for there would be 

 little or no diversity in a Species. But this, we know, is not the case. 

 Herbert Spencer says : " Every Species spreading into a new habit, 

 at coming in contact with new food, exposed to a different tempera- 

 ture, to a dryer or moister air, to a more irregular surface, to a new 

 soil, etc., has its members, one and all, subject to various changed 

 actions, which influence its muscular, vascular, respiratory, digestive 

 and other organs." Now this is simply a clear and comprehensive 

 statement of a fact, which we may see with our own eyes, but we 

 must remember in connection with it, that all animals are not 

 equally sensitive to these influences ; some may show it, little, if at 

 all, whilst in others it will be quite perceptible ; and again, that the 

 migrant or its descendants will attain to the maximum of change 

 which that locality is capable of producing, and never any more. That 

 a further migration is needed to produce more change, that these 

 changes will invariably be in the same direction in the same kind of 

 animal, that migrants going in opposite directions on the globe will 

 come in contact with different influences that will produce different 

 results in the same kind of creature ; and that these influences under 

 which it is living are performing their work and bringing it into har- 

 mony with its surroundings, wholly independent of the creature's will 

 or inclinations. Of these operations the animal may be utterly un- 

 conscious, and even if it were conscious it would be as utterly un- 

 able to resist them. 



Now all the living creatures of the present are, more or less, 

 given to migrating, according as they can accommodate themselves 

 to altered conditions in soil, climate and food, and the ancestors 

 of these did the same ever since they were first originated. What 



