Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: if the birth mean standard of an organ equal 3, and the survival mean 5 when selection is operative, the standard cannot possibly fall below 3 when selection ceases. Mr. J. T. Cunningham criticises pammixis as follows: " The fallacy of this argument is so obvious that it is surprising it should be for a moment accepted. For what is stated of the maxima variations is equally true of the minima. In the absence of all selection the minima variations will be combined in sexual union with variations superior to themselves, and therefore in each successive generation the minimum will be raised. Thus the only possible result of pammixis, on Weis- mann's theory of variation, will be the production of uniformity in a disused or useless organ, and the degeneration or disappearance of such an organ will be absolutely impossible." In an article on "The Factors of Organic Evolution,"f Prof. Geo. J. Romanes calls attention to the fact that he had enunciated the principle of pammixis under the name "Cessation of Selection," as early as 1873. He had not claimed, however, that this cessation of selection could of itself produce the total disappearance of an organ or part. As an instance of this, he supposes a structure to have been raised from 0 to an average of 100, and then to have become wholly useless, so that natural selection would be no longer operative in maintaining the standard. Reversal of selection would then set in, due to economy of growth, and variations 101, 102, 103, etc., would be eliminated, while variations 99, 98, 97, etc., would be favored. To continue the explanation in the writer's own words: "For the sake of definition, we shall neglect the influence of economyacting below 100, and so isolate the effects due to the mere withdrawal of selection. By the conditions of o...