DOUDIFUI. rHHXUMENA OK HERF:1)ITY 383 



CHAPTER XII 

 DOUBTFUL PHENOMENA OF HEREDITY 



I. 'Xenia' and Telegony 



Although it is certainly unnecessary in a theory of heredity 

 to discuss all the possible kinds of phenomena which are with 

 doubtful justice included under this head, I should not like to 

 pass over in silence the consideration of certain presumptive 

 observations, as they have so often been discussed, and were 

 considered worthy of notice by so eminent an authority as 

 Darwin. These refer in the first place to the so-called ' xoiia^ 

 and to the phenomenon generally known as 'infection of the 

 gerni,' — which, in case it really exists, I should prefer to speak 

 of as telegony * 



Focke has used the term 'xenia' to describe those cases 

 in which ' hereditary characters are supposed to have been 

 transmitted by the pollen to the tissues of the fruit as well as 

 to the fertilised egg-cell and the embryo arising from it.' 



Darwin mentioned many instances of this kind, and attempted 

 to account for them by supposing that an emigration of 'gem- 

 mules' takes place from the sperm-cells (pollen-tubes) to the 

 surrounding tissue of the fruit. Focke has collected all the known 

 cases, and on reading them, one receives the impression that 

 they may very likely be deceptive. Blue grains occasionallv 

 occur amongst the vellow ones in cobs of the \ellow-grained 

 maize {Zea) after fertilisation with the pollen of a blue- 

 grained species. It is possible that previous crossings of the 

 two species may have produced this result, which might wrongly 

 be ascribed to the immediate influence of the pollen of another 

 species on the fruit. J. Anderson Henry even thought he had 

 observed that all the flowers in an inflorescence of a white 

 Calceolaria were reddened by the influence of the pollen from 

 a red kind on a single flower of this inflorescence! 



* From T^Xe — at a distance, and 761*0$ — offspring. 



