ENTOMOLOGICAL SOCIETY OF ONTARIO. 43 



being more than ever turned in this direction, illustrations confirmatory of it are being 

 multiplied. In his later writings, Darwin acknowledged that he might not have assigned 

 to it all the importance that it deserves, or the consideration to which it is entitled, and 

 as investigation progresses, its influence in producing variation in nature is becoming 

 more generally admitted. In tropical countries, where life is under a kind of forcing 

 process, this power is strikingly exemplified in insects. There we find variation showing 

 itself in the changed appearance of the same kinds of insects, within shorter distances 

 and in greater numbers. Wallace tells us of one form of butterfly that he traced from 

 the seashore inland until it was scarcely recognizable as the same species, so greatly did 

 it change. This is an exceptional case, but the influence is present, if only the organism 

 is sensitive enough to take the impression. Then consider, that a similar influence is at 

 work to some extent, in some direction, on every form of insect life in the world, and we 

 may form some conception of the tremendous power at work producing variation ; for it 

 is a fact well established by observation of life in domestication, that when a change has 

 been brought about in an organism, it is easier afterwards to produce more and greater. 

 But more ; the same laws that are in operation at present, producing such results, have 

 been at work ever since insects had an existence. Through all the various geological 

 periods in which they have lived, this moulding and modifying influence has been going 

 on, so it is not very surprising that the liability to vary should be so well established in 

 their constitution now. 



Because such a power exists in nature, we have no authority for supposing that it 

 may go on indefinitely, and produce not only different looking things of the same kinds, 

 but also different kinds. That would be contrary to the laws of nature as we know them, 

 also to observation and experience. Each sphere of influence is well defined, whether we 

 can trace it or not. It has a centre where it will be most powerful, and a circumfereace 

 where it may be more weak, but if a change is to be brought about in the organism, a 

 change must be made in its habitat, or it must be made to change its habitat. What 

 difference would be produced by the change would have to be discovered by observation, 

 if the organism survived it, for it is well known that conditions not necessarily fital to 

 life in themselves, might become so if brought about suddenly. Organisms do not chaage 

 themselves by an effort of the will; this influence is external to themselves, and modifies 

 them quite unconsciously to themselves. 



What these influences are, or how they operate in producing a change in organisms, 

 is at present but little known. Past observations point to chemical agency as a powerful 

 factor. Indeed, in one view of it, the surface of the sphere on which we live is one huge 

 chemical laboratory. The process of disintegrating matter and re-compounding it is per- 

 petually going on. Then the various organisms are composed of multitudes of cells that 

 are endowed with the power of choosing and absorbing from inorganic substances the 

 materials required for their own special wants, and passing them on to other cells to be 

 transmuted into the proper ingredients for the producing and sustaining of every organ 

 in each and all, even the most complicated and highly organized beings on the earth. In 

 the case of insects, heat and cold, moisture or its absence, light and obscurity have beea 

 shown to have an influence in changing their size and colour, the result, no doubt, of 

 chemical combinations and actions. We see frequent instances of the same conditions 

 producing opposite effects in different organisms, attributable to the inherent power of 

 cells for differently combining the same materials or transmuting them chemically. And 

 now that the conclusion has at length been reached, confirmed by correct scientific inves- 

 tigation, and one which harmonizes so well with all our observations and experiences, 

 that heat does not come to us through space, but is chemically produced within our at- 

 mosphere in some way by means of the sun's rays, which are electrical, we seem to have 

 got in some measure an explanation of how geologic and climatic influences obtain their 

 power to modify organisms. 



Although external influences are the most powerful originating cause of variation in 

 living forms in nature, the most obvious one, and the one that attracts the most atten- 

 tion, is brought about by the intermingling of existing varieties, which tends to produce 

 yet more abundant variation. The parents being unlike, we see some of the offspring 



