. A text-book of animal physiology [microform] : with introductory chapters on general biology and a full treatment of reproduction, for students of human and comparative (veterinary) medicine and of general biology. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. 110 ANIMAL PHYSIOLOGY. Vines has stated that the equivalent of parthenogenesis takes place in the male cell in plants. Though this may be an objection to the universality of application of Brooks's theory, it does not seem to us to be fatal to it as a whole. As has been pointed out, in a
. A text-book of animal physiology [microform] : with introductory chapters on general biology and a full treatment of reproduction, for students of human and comparative (veterinary) medicine and of general biology. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. 110 ANIMAL PHYSIOLOGY. Vines has stated that the equivalent of parthenogenesis takes place in the male cell in plants. Though this may be an objection to the universality of application of Brooks's theory, it does not seem to us to be fatal to it as a whole. As has been pointed out, in a previous chapter, Darwin held that the differences that caused ultimately the formation of new groups of living forms were the result of extremely slow accumulation of variations, at first very minute. He every- where insists upon this. But, unquestionably, it is just here that the greatest difficulty is to be encountered in the Darwin- ian account of evolution. The chances against the loss of the variation by breeding with forms that did not possess it seem to be numerous, hence various theories have been proposed to lessen the difficulty. Mivart introduced the doctrine of extraordinary births, be- lieving that variations were often sudden and pronounced. That they were so occasionally Darwin himself admitted; but he considered a theory like that of Mivart as a surrender, a resort to an explanation that verged in its character on the introduction of the supernatural itself. (A view that has attracted much attention and caused a great deal of controversy, is that of Romanes, which was intro- duced in part to meet the difficulty just referred to; and to lessen the further one arising from the infertility of species with one another, as compared with the perfect fertility of varieties. It has often been noticed that, though the difference anatomically between varieties might be greater than between species, the above law as to fertility still held. Such a fact calls for ex- p
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Keywords: ., bookauthormillswes, bookcentury1800, bookdecade1880, bookyear1889
