This _absence, in the geological record, of transitional forms,_ is one of the greatest difficulties of the evolutionistic theory. According to the theory, the fossils found in the various layers of rock ought to show gradual modifications, linking the various species of animals and plants in a finely graduated system, with thousands of forms showing in rudimentary structure those organs which in the more advanced forms have become fully developed. However, no such progress from more to less generalized types has been demonstrated, although many trained investigators have searched the fossiliferous rocks for such evidence of evolution. Professor Huxley in his _"Lay Sermons"_ admits that an impartial survey of the positively ascertained truths of paleontology "Either shows us no evidence of such modification, or demonstrates such modification as has occurred to have been very slight; and as to the nature of that modification, it yields no evidence whatsoever that the earlier members of any long-continued group were more generalized in structure than the later ones." LeConte says: "Although the species change greatly, and perhaps many times, in passing from the lowest to the highest strata, we do not usually, it must be acknowledged, find the gradual transitions we would naturally expect, if the change were effected by gradual transitions." He further speaks of the absence of connecting links as "the greatest of all objections" against the theory of evolution. (_"Evolution,"_ p. 234.) This absence of transitional forms between different species has always been recognized as a serious difficulty; and Mr. Darwin, in the attempt to obviate it, succeeds only in showing how very serious it is. These are his words: "Geology assuredly does not reveal any such finely graduated organic chain; and this, perhaps, is the most obvious and gravest objection which can be urged against my theory." Alfred Fairhurst says, in his _"Organic Evolution Considered"_ (p. 93): "According to the theory of evolution, and especially of natural selection, if we start with any organism and trace its history backward, we would find that through an endless number of generations it had been very slightly changing, so that any individual is always a transitional form between its immediate ancestors and its own offspring. This being true, one would expect, if the theory of evolution is true, to find vast numbers of transitional forms connecting earlier and later species in the various periods where fossils are well preserved. This, however, is not true. Species, when they first appear, stand sharply defined. Darwin expresses his disappointment at the absence of transitional forms as follows: 'But I do not pretend that I should ever have suspected how poor was the record in the best preserved geological sections, had not the absence of innumerable transitional links between the species which lived at the commencement and close of each formation pressed so hardly on my theory.'"