'.»8 n m IK S li I'l BS l\ PLANT BREED] STQ 



Iii relation to the above it is suggestive that all the 

 categories which exhibit " xenia " were found to be sehizo- 

 uonous. Those which did not do so were either plant characters 

 (including fruit characters) or such a character of the seed as 

 indentation, which behaves as if it were a fruit character, 

 showing complete correlation (if it may be so expressed) with 

 the plant which bears it. * 



The behaviour of such characters as these, whether Mendel- 

 inn or otherwise, is clearly Less easy to determine than in the 

 case of seed characters ; and so far as the published records 

 go there does not seem to be sufficient evidence to support a 

 definite statement that these characters are really homo- 

 ogonous. 



Correns seems to have shown quite clearly that " xenia " 

 grains invariably yield hybrid plants, which are heterozygotes 

 in respect of the characters concerned in the act of " xenia." 

 From this it follows that the ovum and the combined polar 

 nuclei on the one hand, and the two generative nuclei of the 

 same pollen tube on the. other, bear always the same allelo- 

 morph. 



The [lower of manifestation of an allelomorph in the hetero- 

 sygote ("i" its valency or degree of dominance) was found to 

 vary according to the individual plant and genu cell, and also 

 to differ in different races. This was especially the case with 

 the allelomorphs blue non-blue in relation to t he aleurone lay- 

 er, since heterozygote grains of the same composition (white • 

 blue) m i g hi be either pure while, pure bine, or intermediate iii 

 colour. En the reverse case (blue x white) blue appeared to be 



always fully dominant in first Crosses in the lew cases ex- 

 amined, but itisnol known whet her this is universally t he case. 

 The degree of dominance «>l blue was usually found to be 



* Tin i iIm practioal effect whatever the true explanation may be. 



laina the phenomena by r< 6 n w e i" the t-" I thai in die 



formation of the endosperm two polar nuclei are combined with onlv 



• ■IP- generative nucleu from the pollen tube; and he lupposes thai this 



can in 'nil i predominance "i the Female character 



to wamp the factor introduced from tin- pollen parent. 



