II] structural Characters : Plants 31 



pollen-tube, cases like that of maize are not strictly to be classed as Xenia 

 (see Correns, 58). 



34. Glutenous and starchy endosperms. Wheat. Biffen 

 (27). 



Professor Biffen's researches respecting these important features are 

 not yet completed. The glutenous, translucent, hard type has definite 

 dominance over the opaque, soft, starchy type.. 



35. Single flowers usually behave as dominants to 

 doubles, as in Stocks, Primula, &c. In Carnations the 

 doubleness dominates. 



The most extensive researches on the genetics of double- 

 ness are those of Miss Saunders in the case of Stocks 

 {Matthiola), R.E.C. (20-23). The peculiar phenomena 

 discovered are discussed in a separate chapter {q.v.). 



36. In Phaseolus hypo-geal cotyledons are dominant 

 to epi-geal. Various intermediates in F^. Tschermak 

 (278, p. 54). 



This list and that which follows make no pretension to 

 completeness. Those features are enumerated which either 

 seem of special interest, or have been studied with some 

 thoroughness. Indications respecting many more are to be 

 found in the original papers (see especially for Peas and 

 Phaseolus the writings of Tschermak and Lock ; for 

 Cotton, Balls; for Oe7iothera, &c., de Vries, and jMacdougal 

 (186); for Wheat and Barley, Biffen, and Tschermak; for 

 Maize, Correns, and Lock; for various plants, Correns, and 

 de Vries). 



In the orenus Brassica numerous crosses have been 

 studied by Sutton (262). In his experiments it was found, 

 among other important results, that the bulbing of the 

 Swede, Turnip, and Kohl Rabi disappeared completely in 

 crosses with non-bulbing Kales, and that in /% imperfect 

 bulbing reappeared. Professor Biffen, who is continuing 

 work on the same lines, tells me that in regard to these 

 and similar characters cultural conditions play a great part, 

 and lead to curious and conflicting results. 



