

■ 















342 



Dlt. F. BUCHANAN WHITE S 



mens can usually be obtained exhibiting a more or less perfect 



gradat 



Some of these are pro- 

























» 



. 







bably due to the fact that they are really crosses of the hybrid 

 with one of the parent species ; but this is not necessarily the 

 case, since the influence of one parent may be stronger than that 

 of the other; and differences may also result from an alteration 

 in the sex of the parents. Thus, if A and B represent two 

 species, then A cJ x B 2 may, it is supposed, produce a some- 

 what different-looking hybrid than A? xBcJ does. 



To recognize a hybrid, the student must, in many instances, 

 have an intimate acquaintance with the characteristics of the 

 true species, more especially in the case of closely allied ones. 

 This is very essential, since the books usually describe the more 

 distinct forms only, and frequently seem to ignore the insensible 

 gradations which connect the hybrid with its parents : not that 

 they really ignore them, but from the difficulty of expressing in 

 words characters that the trained eye can more or less easily 

 perceive. 



The rank to be ascribed to hybrids and the system of nomen- 

 clature to be adopted are points on which it is desirable that 

 more unanimity and uniformity should obtain amongst botanists. 

 Taking Nyman's ' Conspectus * as a sample of a not uncommon 

 method, it will be found that some hybrids (e. g. S. rubra and 

 S. Doniana) are given full rank and numbered as species ; whilst 

 others, of equal importance, have no such position. Some other 

 authors merely indicate the occurrence of hybrids and do not 

 describe them; whilst among those who give hybrids a rank 

 nearly or quite equal to species, some, as Audersson, place them 

 in the groups to which they are most entitled to belong, but 

 others, as Wimmer, keep all the hybrids together. 



Then as regards the nomenclature, Andersson and many others 

 adopt distinct names, which do not in any way indicate the real 

 or supposed parentage ; but Wimmer, on the other hand, re- 

 pudiates, as a rule, all such names, and uses for the hybrids a 

 combination of the parental designations. In many respects 

 there is much advantage in Wimmer' s method ; but even he has 

 not been able to employ it uniformly, and was obliged to use 

 other names in certain cases where the parentage is doubtful ; 

 and moreover in some instances the compound name that he has 

 used is erroneous and misleading. Wimmer's plan also entails a 

 breach of the law of priority. Under these circumstances, whilst 





■ 





■ 

 ■ 



? ■ 













, 















■ 















■ 



■ 







h 



h 





■ 



