8250 



Northern Entomological Society. 



first inanimate matter became animate. If, however, the phrase ' origin of species ' be 

 considered to relate only to the assumption by animals and plants of those exact forms 

 which they now present to our observation, it is tolerably certain that careful reasoning 

 from exact data will lead ultimately to correct notions as to the relationship by descent 

 of races, and consequently to the origin of existing so-called species. Many years before 

 Darwin promulgated his doctrine of 4 selection of races' I had formed my own conclu- 

 sions relative to the now fixedness of species, and being unable to find any support in 

 nature to the theory of uniform * progressive development,' I framed the hypothesis that 

 species or forms are, and ever were, mutable, sometimes advancing in the scale of 

 organization, sometimes retrograding, but always varying, — the sons from their sires, 

 and the sires from the patriarchs of their respective races. I termed the theory 1 The 

 Mutability of Species, or the Mutation of Generations.' 



"Mr. Darwin has dwelt ingeniously and satisfactorily upon one cause for the 

 alteration of forms of life, viz. that of the greater fitness to surrounding circumstances 

 in the struggle for existence of certain slight modifications of structure. He has 

 dwelt so exclusively upon this branch of the great subject as almost to lose sight of 

 other agencies; for example, the direct influences of climate and food, and the accu- 

 mulative effects of those apparently causeless individual variations that take place at 

 every generation. It is to the latter law that I am myself disposed to attribute the 

 greater portion of the mutation of forms or of so-called species. Let us suppose a 

 separation by an intervening ocean of the two portions of a large tract of land that 

 were previously united, and let us further suppose the whole of this land to have been 

 inhabited at the time of the cataclysm by some race, say of geodephagous insects. 

 We will distinguish these two now separated portions of land as the eastern and the 

 western. The generations of the insect in question that came into existence after the 

 separation of the land would succeed each other as their ancestors had previously done, 

 each individual differing somewhat from the parents and each pair hauding down to 

 its progeny a structure embracing what may, for the sake of explanation, be termed 

 the hereditary typical form, together with a portion of the joint peculiarities of the 

 parents themselves, and combined with that certain degree of individual peculiarity by 

 which peculiar facies or appearance the new-born individual would be known to the 

 critical eye from all other individuals of the same race. The conjoint effect of here- 

 ditary transmission of form and individual peculiarity will have taken in the eastern 

 tract one direction, in the western probably another: food, climatic conditions of heat 

 and moisture, and natural selection, will have acted directly and indirectly in giving 

 some bias in respect of form, size, colour and appetites, which, in the individuals of 

 either one of the restricted districts, will have assumed a degree of uniformity owing 

 to the interbreeding. In the meanwhile, different influences have been operating in 

 the other isolated district, and the mutable tendency of the race, on the ordinary doc- 

 trine of chances, will, almost as a matter of inevitable certainty, have set up a bias 

 differing in some respects from that of the generations in the opposite district. It 

 thus results that the longer the period of time during which separation has existed the 

 greater the chance of divergence, and if the races in the two separated tracts of land 

 have been kept apart for a long period of time, say for some thousands of years, we 

 may reasonably look to find a very sensible divergence of forms, sufficiently so to set 

 naturalists disagreeing as to whether they ought to call the forms by two different 

 specific names, or whether the two should be considered varieties merely of each other. 

 This is the view I took in reference to mutation of forms or transmutubility of species, 



