Retrograde Varieties 123 



by cutting, and this leads to the distinction of 

 ^ ' seed-varieties ' ' and ' ' vegetative varieties. ' ' 

 In the first case the inheritance of the special 

 characters through the seeds decides the status 

 of the variety, in the latter case this point is left 

 wholly out of consideration. 



Leaving aside all these different types, we 

 are concerned here only with the " seed-varie- 

 ties ' ' of pure origin, or at least with those, that 

 are supposed to be so. Hybridization and 

 vegetative multiplication of the hybrids no 

 doubt occur in nature, but they are very rare, 

 when compared with the ordinary method of 

 propagation by seed. *^ Seed-varieties '' may 

 further be divided into constant and inconstant 

 ones. The difference is very essential, but the 

 test is not always easy to apply. Constant 

 varieties are as sharply defined and as narrowly 

 limited as are the best wild species, while in- 

 constant types are cultivated chiefly on account 

 of their wide range of form and color. This 

 diversity is repeated yearly, even from the 

 purest seed. We will now discuss the constant 

 seed- varieties, leaving the inconstant and ever- 

 sporting types to a subsequent lecture. 



In this way we may make an exact inquiry 

 into the departures from the species which are 

 ordinarily considered to constitute the essential 

 character of such a constant and pure seed- 



