408 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



processes of fertilization are no doubt conditioned by the physical 

 relationship of the sexual organs especially when there is differ- 

 entiation with respect to time of development. 



A serious objection to the conceptions of Jost and ]\Iorgan is the 

 very obvious fact that close relationship of the sex organs is 

 equally present in all hermaphrodite plants, large numbers of 

 which are self-fertile. In fact, in a single strain of plants, as in 

 chicory, self-fertile and self-sterile individuals may exist. Further- 

 more, there may exist all degrees of cross-fertility and sterility 

 among these self-sterile plants. These facts, especially, make it 

 fully evident that there can be no general or very definite appli- 

 cation of the doctrine either of individual stuffs or of purely 

 individual cytoplasmic relations to the facts of relative sterility 

 and fertility. These conceptions do not adequately distinguish 

 self-fertile plants from self-sterile, and give no evident reason for 

 the development of one or the other type. 



Special phases of the phenomena of sterility and fertility 

 Before attempting to pass judgment on the very suggestive 

 views already noted, or attempting to formulate any new con- 

 ceptions, the different phases of the phenomena of sterility and 

 fertility may be especially considered. 



The relation of cross-incompatibility to self-incompatibility. — The 

 results I have obtained with chicory indicate that the physio- 

 logical processes involved in the self- and cross-incompatibility 

 seen in this species are fundamentally of the same general nature. 

 The results are quite the same in both cases. As far as tested 

 there seems to be a very general cross-sterility in those families 

 whose individuals are mostly self-sterile. This is seen in the results 

 with the {A X C) series and with the generations of the variety 

 red-leaved Treviso. As far as known, at least some degree of 

 physiological self-incomjiatibility always exists within a. species 

 or strain showing cross-incompatibility. Usually the .^j^hnomenae 

 of self-incompatibility is much the more pronounced; in fact so 

 much so that the phenomenon of cross-incompatibility between 

 closely related plants of seed origin (not involving dimorphism, 

 etc.) was not believed to occur previous to Correns' report in 1912. 

 Unless it can be shown that cross-incompatibility such as exists in 

 Cardamine and Cichorium can exist without any self-incom- 



