A. B. Stout 97 



(Stout, 1916) shows that the inter-fertilities and sterilities do not fall 

 into four nearly equal classes such as Correns has grouped them. 

 Compton (1913) has also pointed out that if Correns' assumption holds, 

 one-fourth of the Fi generation which he studied should have been 

 self-fertile. On this particular point Correns' data are incomplete : he 

 seems to consider all plants self-sterile, but his report includes data for 

 self-pollinations of only 13 out of 60 of the Fi generation. Of these, 

 however, three were partly self-fertile. The interpretation that self- 

 sterility and cross-sterility are due to a few line stuffs that are transmitted 

 as single hereditarj^ units is obviously inadequate. The conclusion, 

 however, has been given considerable credence, especially in Mendelian 

 circles. 



East (1915a and h) very soon pointed out the inadequacy of Correns' 

 interpretation, and formulated a " near Mendelian " interpretation for 

 the almost complete self-sterility and the almost complete cross-fertility 

 which he observed in h^^brids between two species of Nicotiana. While 

 discarding the conception of factors directly concerned with fertility 

 and sterility as such, East considers that these conditions arise as 

 indirect properties of Mendelian units ; plants are self-sterile because 

 the male gametophyte produced by a plant can possess no hereditary 

 unit not possessed by the somatic cells of the pistil. He assumes that 

 this degree or element of similarity between pollen-tube and pistil in 

 self-pollination prohibits the formation of secretions in the pistil which 

 are necessary for the nourishment and growth of the pollen-tubes. 



As to the facts of breeding performance, we may note that neither 

 East nor Correns gives adequate data as to the fluctuations in the degree 

 of fertility, or in the behaviour of pedigreed lines of descent from self- 

 sterile parents of a variety or a species, and there have been no data 

 published regarding the behaviour of pedigreed lines of descent from 

 self-fertile individuals which originated sporadically from self-sterile 

 parentage. A few such plants were in evidence in the F^ crop studied 

 by Correns quite as I found them in chicory. 



It is especially to be noted that there are no published data 

 regarding the performance with reference to sterility and fertility of 

 cultures of the so-called self-sterile species Antirrhinum molle and 

 Nicotiana Forgetiana. Detailed studies of the performance of these, 

 as well as of other species reported self-sterile, are greatly to be desired. 



Moore (1917) recently reports that: "The species of Tradescantia, 

 alsike clover, alfalfa, and Shirley poppy showed different degrees of self- 

 sterility. Tradescantia was completely self-sterile ; in alsike clover about 



