8. Ikkno 51 



i/-type& In uther words, of the h\ offHprin^ 00 und gg will l>clung to 

 G-typca and ^/-type«, rt»8|K»ctivi'ly, whilst Og will belong jwirtly to the 

 one and jjartly U> the other. Thus the ntiiiilHT t»f plants of hnth tyj>eH 

 Mhould be theoretically tM|ual to each other, which acconiM, a« wt? have 

 alremly 8een. with the fact n-ally obsrrvrd. 



This explanation of the behaviour of our cross in /', and F.^ '\h 

 naturally mere hypothesis which needs to be subjecte<l to ex|>eriinental 

 verification. The latter would b** however extremely difticult, if not 

 absolut'cly im{x>ssible, but I intend to continue my work in this 

 direction, as far as I can. 



To summarise, the formation of the two ty|)es of aitkins in F, is not 

 to be looked uixm jus the ri'sult of segregation of the aitkin chanicter ; 

 the occurrence of the latter process in F., luis however been clearly 

 proven, though the ratio of the two tyjx's pro<hiccd in each of the 

 three kinds of fertilisiition is (juite different from what we might have 

 expected in usual Mendelian cases. 



B. Results of the Hybridisations done in 1911. 



As already stated (p. 36) I have repeated in 1911 the same hybridisa- 

 tion done in 1910. The female plant wiis the very s<ame tree used in 

 1910; whether or not the male plant was just the same as that used in 

 1910 is now unknown, but it belongs, at least, to the same vegetative 

 line (in the sense of Fruwirth) or the same clone (Webber) as the latter, 

 because in 1911 all male plants of S. gnicilistijla in our Botanical 

 Garden were exclusively derived from the cuttings of the same plant 

 used in 1910. This hybridisation succeeded pretty well, and I got 

 nearly fifty seedlings. They were, however, contrary to the result of 

 the hybridisation in 1910, not hybrids at all, at least externally. They 

 were nothing but S. niultinei^vis, and when they came to flowering, all 

 of them have proven, to my great astonishment, to be female individuals 

 without exceptions, or in other words, the offspring were of purely 

 ttuUenial type, so-called /a^se (Millardet) or unilateral hybrids (de Vries). 



The production of either purely paternal or maternal j)lants as the 

 results of hybridisation — what Bateson calls " Monolepsis"' — h;is been 

 sometimes met with by various authors. Thus Gartner' obtained from 

 the hybridisation Melandriuni rubruui % x Sileiie noctiflora ^ only 



* Report to the Kvolution Committee of the Royal Society, lleport I, 1902, p. loo. 



* Versuche und Beohachtungen Hber die liaxtdrderzeuyuuy im Pjlanzenreich, Stuttgart, 

 1849, p. 37. 



4—2 



