358 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



It should be noted that Baur ('11, p. 212) had already suggested 

 a simple Mendelian explanation for the behavior of self-sterility. 

 A7itirrhmum molle, which is ''streng selbststeril " when crossed with 

 the self- fertile species A. majtis, gave, he reports, only self- fertile 

 Fi progeny while the F2 consisted of both self-fertile and self-sterile, 

 the former being in the greater number. Baur has not published 

 any data regarding the number of plants, the variations which 

 they exhibited, nor is there any evidence on the very important 

 questions of self- and cross-sterility in the species Antirrhinum 

 molle. Lotsy ('11) has, however, grown F2 generations of these 

 hybrids and reported that such wide diversity exists in their self- 

 fertility and self-sterility that at least in certain lines of descent 

 no two individuals can be considered the same. Compton ('12, 

 '13), likewise, supports the view that self-fertility (in Reseda) is a 

 simple Mendelian dominant over self-sterility. He considers 

 that it is even simpler than Correns conceives it to be in that the 

 self-sterile plants are really recessives possessing absence of sub- 

 stances either stimulative or nutritive to the growth of the pollen 

 tubes, and that self-fertile plants, which do exist, may or may not 

 breed true. Compton's conception of the simple presence and 

 absence of a substance stimulating growth attempts to account 

 for self-fertile and self-sterile plants, but is hardly considerative 

 of any phenomena of cross-fertility or cross-sterility, especially 

 among plants self-sterile. Compton has not published the data 

 of his investigations. 



At this stage in the study of the phenomena of self-sterility 

 East presented data showing that self-sterility may be almost 

 complete among a culture of hybrid plants which exhibit feebly 

 if at all the phenomena of cross-sterility. East, although formerly 

 considering that Nicotiana alata grandiflora and N. Forgetiana, 

 together with other Nicotiana species, are fully self-fertile, finds 

 ('15) that cases of self-incompatibility may have appeared in at 

 least one of these species and that from one cross four generations 

 totaling over 500 plants were tested and found completely self- 

 sterile. When crossed among themselves they were almost com- 

 pletely fertile. However, from the data given l)y East, it appears 

 that no systematic crossings were made in the Fi, and that only 

 twenty plants of the F2, twelve of the F3, and ten of the F4 were 

 used in such crosses; willi these, however, 289 combinations are 



