Dec, 1919] Dieciousness in Thalictrum Dasycarptim 29 



factors can produce any number of forms of morphological 

 expression because of the different physiological states somehow 

 set up in the protoplasts by the presence of the different gall- 

 forming insects. So sexuality appears to be a differential con- 

 dition or state of greater or lesser degree of intensity and not a 

 set of discreet male and female determiners. In the living 

 tissue we have a positive or negative state set up which we call 

 femaleness and maleness mainly because the characters expressed 

 show a dimorphism. It may even be assumed that for the 

 greater part of sexual characters there are no separate factors 

 for the male and female characters, but that the factors present 

 are merely modified in their activity thru the influence of 

 the male or female state established at the time. The maleness 

 or femaleness or neutral condition of a cell or tissue suggests, in 

 a vague way, some analogy to positive and negative electricity 

 in physics or acid and alkaline substances in chemistry. The 

 dimorphism which appears is probably due to the hereditary 

 mechanism or factors acting under the influence of a male or 

 female condition. If growth is taking place while the given 

 state is set up male characters or female characters of a per- 

 manent type appear. In the lowest sexual forms sexuality is 

 commonly developed in the cell when growth is completed and 

 so no dimorphism of structure can appear. In such plants as 

 the more specialized Spirogyras, altho no sexual dimorphism 

 is apparent in the cells until shortly before conjugation, because 

 the cells and filaments are apparently in a neutral state while 

 growth is going on, the conjugation tubes nevertheless do show 

 a dimorphism apparently because the cells are plainly in a male 

 or female state at the time. It is well known that in certain 

 Spirogyras lateral conjugation frequently takes place between 

 adjacent cells of the same filament. In such cases sexuality 

 cannot be determined until near the end of the vegetative 

 period, or if it is determined it is reversed again in certain cells. 

 The sexual state, either male or female is set up in neutral cells 

 without any reference, apparently, as to the presence of a male 

 or female determining factor in a special chromosome. We may 

 compare such cells to a delicately poised balance in which a 

 slight internal physiological difference will tip the beam in one 

 direction or the other. In the case of extreme diecious sporo- 

 phytes it is possible that the sex is thus determined in the egg 

 even before fertilization takes place. But in such species as 



