The _Xanthium Wootoni_, above referred to, with only part
of the prickles of Xanthium commune is also a very curious instance of
the demonstration of the compound nature of a character.
Summarizing the conclusions that may be drawn from the evidence given in
this lecture, we have seen that varieties differ from elementary species
in that they do not possess anything really new. They originate for the
greater part in a negative way, by the apparent loss of some quality,
and rarely in a positive manner by acquiring a character, already seen
in allied species. These characters are not of the nature of [153]
morphologic entities, but are to be considered as physiologic units,
present in all parts of the organisms, and manifesting themselves where
ever occasion is afforded. They are units in the sense that they may
appear and disappear singly. But very often they are combined to yield
compound characters, which are capable of analysis. Opportunities for
such an analysis are afforded by these groups of cultivated varieties,
of which some members show a single distinguishing quality, or a number
of them.
[154]
LECTURE VI
STABILITY AND REAL ATAVISM
It is generally believed that varieties are principally distinguished
from species by their inconstancy. This conception is derived from some
special cases and transferred to others, and in its common form this
belief must have originated from the confusion which exists as to the
meaning of the term variety.
Pages:
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164