CARBOHYDRATE-NITROGEN RATIOS WITH RESPECT TO THE SEXUAL EXPRESSION OF HEMP

Most of the recent work on the determination of sex in the higher plants has been done by cytologists and geneticists. These investigations have resulted in the chromosome theory of sex inheritance and sex determination, which is supported by much evidence in the dioecious forms of the higher plants. Any adequate theory of sex inheritance and determination in the angiosperms must do more than account for the usual approximate 1 : 1 ratio of the sexes in dioecious plants. It must also explain the reversal of sexes within the so-called dioecious plants and the determination and development of both types of sporophylls on the same plant, as in the monoecious types. It should even explain the development of both types of sporophylls within one flower, as is the case with the majority of the angiosperms. The segregation of the microsporophylls and the macrosporophylls to individual plants should be considered the exception and not the general case. Any theory of sex determination based only on dioecious types is subject to many exceptions and criticisms. The absence, or apparent absence, of allosomes in many dioecious plants and the frequency of reversal from the staminate to the pistillate condition, or vice versa, in forms in which allosomes have been reported, have led to differences of opinion as to the final importance of the "sex chromosomes" in sex determination in the dioecious angiosperms. The reversal of the sexes in dioecious plants indicates that sex determination and inheritance may result from the action of two different, but closely related, sets of factors in the development of these plants. The prevailing 1 : 1 ratio of the sexes indicates that a genetical tendency to produce one or the other type of flower is probably inherited in a strictly Mendelian manner. The evidence from the development of intersexes under certain environmental conditions shows clearly that the final display of the staminate or of the pistillate condition is determined by physiological as well as by genetic factors, even in dioecious plants. Probably the development of staminate and pistillate flowers is more dependent on physiological factors in monoecious than in dioecious plants. In plants with perfect flowers the development of stamens and pistils is probably chiefly dependent on physiological factors. Indeed it would be difficult to explain the determination of the