doubt, if any had existed, as to the identity of the wild and domesticated stocks in Europe, and we may safely proceed to compare the physical characters of these races as varieties which have arisen in one species." (Unity, etc., pages 32, 33.)
As will be remembered, the leading instance of reversion cited in the Origin of Species is the tendency of fancy breeds of pigeons to return to the "blue rock," from which fact Mr. Darwin concludes that to be the original stock. As the hog is a more highly organized animal than the pigeon, this flexibility of species in it is more striking than in the oviparous pigeon.
As suggested above, it is probable that much of the interest excited by the Origin of Species was due to the brilliant exposition of Mr. Huxley; but, aside from that, unquestionably the chief reason that so many without the ranks of professional biologists discussed its reasoning so eagerly and earnestly was the bearing it had on the genesis of man. Mr. Huxley's lectures touched almost every branch of modern science—zoölogy, bacteriology, geology, sociology—all were equally familiar to this, perhaps the greatest public lecturer of our race, but to none of them did the laity give the rapt attention that was and still is given to evolution. The bearing of spontaneous variation among the lower orders of living organisms on the human race was clearly seen by Dr. Cabell, and the object of his work was to offset the arguments of those who claimed a plurality of genera among men by showing that lower organisms develop varieties without the intervention of any supernatural creative power. As a necessary inference from this, and, indeed, that it should have any bearing at all on the problem of humanity, he must have held that there was no radical difference between man and other animals.
The similarity between the arguments used by Cabell and those to be used a few months later by Darwin is striking, and equally remarkable is it that both should have foreseen objections to the theory, and that these objections are essentially identical. The difficulty of defining species as distinct from variety impressed them both; the alleged sterility of hybrids, an objection answered by both by showing it not to be invariable; the lack of intermediate forms, attributed by Darwin to the imperfection of the geological record and by Cabell to imperfect geographical knowledge, and several similar instances, can not fail to impress an attentive reader.
This neglected volume is a wonderful monument of painstaking labor and erudition, and although overshadowed by the more extensive works that appeared a few months later from the great English writers, it is one in which American biologists may take pride. Most remarkable, however, is the fact that it was greeted with de-