Page:Popular Science Monthly Volume 63.djvu/224

220 at least, is still very strongly of the belief that the investigator of reproductive cells holds the keys of evolution, and he even finds it remarkable that a general cytological explanation of these 'principles of inheritance' was not suggested before. According to Professor Wilson the facts discovered by Mendel, that in some hybrids, characters of the parents are not permanently combined, are explainable by the 'normal phenomena of maturation,' that is, if we admit that 'individual chromosomes stand in definite relation to transmissible characters,' and that the 'reducing division' by which the reproductive cells are formed 'leads to the separation of paternal and maternal elements and their ultimate isolation as separate germ-cells.' This would be important if true, but the Mendelian facts are unable to accept this proffered support of cytological theory, because they have already demonstrated its falsity.

The commonly accepted view of organic descent may be illustrated by a simple diagram which indicates that a single individual may

inherit characters from all four of its grandparents. Professor Wilson's explanation of Mendel's law would deny this possibility, and would limit the descent of all individuals to two grandparents, so that, the form of our family tree would be completely altered.