liv THE ANIMAL KINGDOM. 



often operates too slowly ; there are gaps which have been, so to speak, intentionally 

 left by Nature. Moreover, natural selection was, as usetl by some writers, more an 

 idea than a vera causa. Natural selection also begins with the assumption of a ten- 

 dency to variation, and presupposes a world already tenanted by vast numbers of ani- 

 mals, among which a struggle for existence was going on, and the few were victorious 

 over the many. But the entire inadequacy of Darwinism to account for the primitive 

 origin of life-forms, for the original diversity in the different branches of the tree of 

 life-forms, the interdependence of the creation of ancient faunas and floras on geologi- 

 cal revolutions, and consequent sudden changes in the environment of organisms, has 

 convinced us that Darwinism is but one of a number of factors of a true evolution 

 theory ; that it comes in play only as the last term of a series of evolutionary agencies 

 or causes ; and that it rather accounts, as first suggested \)\ the Duke of Argyll, for the 

 preservation of forms than for their origination. We may, in fact, compare Darwinism 

 to the apex of a pyramid, the larger mass of the pyramid rejiresenting the true theory, 

 or complex of theories, necessary to account for the world of life as it has been and 

 now is. In other words, we believe in a modified and greatly extended Lannirckiau- 

 ism, or what may be called neo-LaTnarckianism. 



It is not the design to present here arguments for this tlieoiy of evolution, but to 

 show what Ameiican authors have written in favor of the incidental, as well as the 

 periodical, recurrence of sudden or quick evolution, through changes in the environ- 

 ment, as opposed to the supposed continuous action of natural selection. 



Without doubt, that able and philosophic naturalist, the late S. S. Haldeinan, was 

 not unfavorable to a modified form of Lamarckian views as to the transfoi'mation of 

 species. His Enumeration of the recent fresh-water Mollusca which are common 

 to North America and Europe, with Observations on Species and their Distribution, 

 was published as early as January, 1844. He takes occasion to remark : " I pretend not 

 to offer an opinion for or against the Lamarckian, being more anxious to show the in- 

 sufficiency of the standing arguments against it, and the necessity of a thoi'ough 

 revision of them, than to take a decided stand (upon a question which I regard as open 

 to farther discussion) before its facts have been carefully observed, or the resulting gen- 

 ei'alizations pro])erly deduced ; so that, whether it be admitted or not, it is entitled to 

 the benefit of all the discoveries which can be brought to bear upon it; and, on this 

 account, I have not hesitated to give a slight sketch of the theory of transmutation, as 

 I conceive it to be modified by some of the results of modern science." 



In the course of his essay ho remarks : " The reason why the lower orders still 

 exist is to be looked for in the fact that they are fitted for the circumstances under 

 which we find them." Again he says : " Although we may not be able, artificially, to 

 produce a change beyond a definite point, it would be a hasty inference to suppose that 

 a physical agent, acting gradually for ages, could not carry the variation a step or two 

 farther; so that, instead of the original, we will say four varieties, they might amount 

 to six, the sixth being sufficiently unlike the earlier ones to induce a naturalist to con- 

 sider it distinct. It will now have reached the limit of its ability to exist as the former 

 species, and must be ready either to develop a dormant organic element, or die ; if the 

 former is effected, the oscillating point is passed, and the species established upon the 

 few individuals that were al)le to survive the shock. If the physical revolution sup- 

 posed to be going forward is arrested, or recedes, the individuals which had not passed 

 the culminating point remain as a fifth variety, or relapse towards their former station ; 

 whilst the few which have crossed the barrier remain permanently beyond it, even 



