80 



Species and subspecies, on the other hand, are units isolated 

 by nature. It is not a matter of taste how many species exist, 

 though one might imagine so, to read the current botanical 

 literature. Ultimately we shall have to know how many forms 

 stand physiologically isolated from one another, and these will 

 be recognized as true species. Subspecies are similar, except 

 that at some point the isolation is as yet incomplete. The word 

 variety may as well be abandoned as a distinct category ; but it 

 is useful as a refuge when we do not know the proper status of 

 a plant. 



The " form " (forma) is really something different. As I under- 

 stand it, it expresses a phase existing wholly within specific 

 limits ; a result of the variability of the organism, spontaneous or 

 induced by external conditions. I thoroughly believe in the 

 classification and naming of forms, as the study of these phe- 

 nomena greatly assists us to understand the origin of species ; 

 but the form is not to be confused with the subspecies or variety 

 proper. I think, myself, that even names given to forms should 

 be recognized when it is found that they represent valid sub- 

 species or species ; but if there is to be a distinction made and a 

 line drawn, surely it must be between the subspecies and form ; 

 not between the species and subspecies. This is the more neces- 

 sary, because while we can usually (or at least frequently) tell 

 when we are dealing with a form, it is much harder to draw the 

 line between species and subspecies. The evidence for the status 

 of the form may be simple and positive ; that for the status of the 

 species is negative, and to affirm that it does not anywhere inter- 

 grade with its nearest ally, would require knowledge that we 

 rarely possess when describing. 



The trouble about the homonyms results from the practice of 

 suppressing a name because it has been used in a varietal sense 

 under a different species of the genus. This seems to me an un- 

 necessary and mischievous procedure, and I live in the hope that 

 it will at length be universally condemned. The law of homo- 

 nyms is at best a necessary evil, and it should be made to bear 

 on us as lightly as possible. 



East Las Vegas, N. M., May 26, 1901. 



