stout: pollinations in cichorium intybus 407 



sudden and repeated changes in preparation for each self-fertiliza- 

 tion. Any further modification of this general view which should 

 assume that different grades or degrees of activity of single units 

 or groups of assumed hereditary units can account for the phe- 

 nomena of feeble fertility only makes more obscure the physio- 

 logical processes, and, would not in any case enable one to, predict 

 what the behavior will be in any species or strain. 



East's observed results are of special interest in showing that 

 even in interspecific hybrids the character of self-sterility may 

 appear in all (or nearly all) of the ofTspring among which there is 

 nearly complete cross-fertility. In his results cross-sterility is 

 almost entirely absent; in Correns' results cross-sterility is strongly 

 in evidence as it is in chicory. These apparent discrepancies 

 emphasize the sporadic and fluctuating nature of self-sterility and 

 demand a theory which shall account for the relations of cross- 

 sterility and self-sterility as they appear in breeding. 



It is evident that there is much in the phenomena of self-sterility 

 that favors the general basis of the conceptions of Jost and Morgan. 

 It is most obvious that self-incompatibility, as indicated by the 

 self-sterility of such hermaphrodite plants as Eschscholtzia, Carda- 

 mine, Reseda, NicoHana, Beta, Cichorium, etc., and in such animals 

 as Ciona intestirialis, has appeared, when from the nature of the 

 case, the reproductive organs and gametes are of the closest possible 

 physical relationship. In each individual they are produced by, 

 and in large measure composed of, somatic tissues with the same 

 hereditary complex, and when borne in the same flower with a 

 close cytoplasmic and sap relationship. The evidence seems clear 

 to Jost and Morgan that differences in the hereditary complex of 

 spores, gametophytes, and gametes are not essentially involved, 

 and that the causes of the incompatibility are to be sought in the 

 conditions developing from the close physical relationship of the 

 sex organs. In this sense the constitutional conditions present 

 may involve lack of some sort of constitutional (sex) differentiation 

 quite as Jost assumed. It appears that this condition also may 

 even give various grades of gametic incompatibility as in Ciona 

 intestinalis. This suggests that certain phases of fertilization are 

 to be considered as influenced by the close relationship of the 

 organs concerned. Whatever may be the affinities of the elements 

 of the germ plasm in the act of cell fusion, certain phases of the 



