234 M. Ch. Naudin on Hybridity in Plants. 



would be fertile or not ? I can affirm this, that I have never 

 obtained a hybrid which manifested the least tendency to 

 form a specific stock. 



At present I only know a single instance which might 

 serve as a basis for the hypothesis of fixation of hybrids. 

 Still this fact is doubtful ; it is that of ^gilops, closely allied 

 to wheat, which was cultivated at the Museum about ten 

 years, during which the successive generations did not pro- 

 duce any appreciable modification. 



It remains to be proved whether the ^gilops cultivated at 

 the Museum speltceformis, Jord.) is really a hybrid, 

 and that it does not modify itself during a long series of 

 generations: it would be an exception; but this very general 

 rule would not be weakened, at least so long as the fact 

 remained isolated. 



(7.) Is there any precise limit between Hybrids and Crosses ? 



Most hybridologists insist on making a distinction be- 

 tween hybrids and crosses, and nothing could be more easy 

 to understand ; the hybrid results from the crossing of two 

 distinct species, two true species, as M. Eegel says — the 

 crosses from that of two races or varieties. 



Theoretically, nothing is more clear ; in practice, nothing 

 is more difficult than the application of these two words. 



For example, ought the produce obtained by the crossing 

 of the Cantaloup Melon and Netted Melon, that of the Netted 

 Melon and Dudaim, that of Dudaim and Cucumis PancJie- 

 rianus, or even that of Datura Stramonium and of Datura 

 Tatula, &c., to be called hybrids or crosses ? This question 

 gives rise to another, that of the distinction of species, 

 races, and varieties, an everlasting subject of dispute among 

 naturalists, which too often ends in a war of Vfords un- 

 worthy of the science ; to settle which, it is necessary to 

 turn to the examination of what is understood by the term 

 Species^ Bace, and Variety, 



(8.) What^ therefore^ is a Species, Race, and Variety ? 

 Let us start at the very origin of the notion of species, 



