270 MR. BALL ON PLANTS COLLECTED IN MOROCCO. 
inference from observing that the differences by which they are 
distinguished are not greater than what we observe among the 
s, 
the same external conditions, usually show greater constancy in 
their characters than cultivated varieties, developed under conditions 
of a less permanent kin 
varieties enumerated in works of systematic botany are 
almost invariably races, such as those above referred to, and under 
se in 
France and Germany, who start from the assumption that differences 
which are preserved in cultivation, when a plant is raised from seed, 
are epi of specific distinctness. 
great practical difficulty for the 5 bare botanist arises 
from the ‘embee of forms more widely ent from recognise 
species age varieties usually are, Scagushad by w well-marked 
more viady diffused spec is ¢ may arise siahen ‘ton 
remarking that the ities affect ae habitually subject to much 
variation in the same group, or that at s ace or places within the 
are co y intermediate forms, 
suggesting the or _ the doubtful plant has originat 
here, a o diffuse itself through a larger area 
without exhibiting meen links is for suc rm 
as 
these that the term subspecies appears ‘to be desirable in descriptive 
inent aut 
well-Syme’s “ English Botany,” and its adoption in Dr, Hooker's 
modifications which appear to me desir eS and which I trust may 
obtain a 2 Serene of those entitled to rank as legislators in 
natural se 
oe as no plants deserve to be classed as subspecies 
which do not present obvious differential characters, easily 
recognisable by the practised eye, and inasmuch as a sub- 
species s§ i i 
