Page:Popular Science Monthly Volume 77.djvu/361

Rh for constant intermediate hybrid races which I think has never before been mentioned. In crossing species of the genus Nicotiana, I have had plants develop from seed that have apparently been formed apogamously, that is, formed from an immature egg cell without fertilization. It is evident that this is induced by the extraordinary irritation of foreign pollen. The true hybrid plants that are formed are generally blends in the first generation. The question, then, arises: May not the. difficulty of maturing sexual cells in a wide cross sometimes cause apogamous development and therefore a continued propagation of a constant and uniform race?

All but the last of these suggestions may also be pertinent in the case of varietal crosses where there is said to be a blending of characters that deal with size. I am not certain, however, that all the so-called blend hybrids might not show segregation if studied in large numbers. I have found such segregation in size characters in crosses of both maize varieties and of tobacco varieties.