1897] ORIGIN OF SPECIES AMONG PLANTS 167 
are theoretically assumed to be, constant.” One or more of these 
characters may be found on another species, which in a similar 
manner is known by its collection of constant characters. : 
What may have been their origin, and how the survival and 
maintenance of any superficial characters of a plant have been 
secured, are philosophical questions with which the systematist has 
no concern at all. 
Useless Characters.—Before showing that the hypothesis of 
natural selection is superfluous in the origination of varietal charac- 
ters, let us turn to the descriptions of plants given in some standard 
work, say, Sir J. D. Hooker’s “ Students’ Flora of the British Isles.” 
It will be found that many characters are taken as specific or 
generic which cannot, with any show of reason, be regarded as 
specifically useful; such as the numerical excess or deficiency in 
the number of parts in the floral whorls; eg. Gentiana campestris 
is described as having the calyx “four-partite”; while in G. amarella, 
it is “ five-lobed ” ; but fours, fives and sixes may be often found on 
one and the same plant, as in acorymb of elder flowers, due to an 
accidental deficiency or excess of nutriment, respectively ; and no 
vital importance can be attributed to the trivial specific distinc- 
tion between “ partite” and “lobed.” Such illustrations of quite 
unimportant characters regarded as specific can be multiplied to 
any extent; but they are some of the very characters which 
Darwin admits are not due to natural selection. He says: 
—“We thus see that with plants many morphological changes 
may be attributed to the laws of growth and interaction of parts, 
independently of natural selection.”* They are, in fact, simply 
the inevitable results of a response to environmental conditions, using 
the term in the broadest sense. 
With regard to such indifferent characters being hereditary, 
Darwin first says that he “felt great difficulty in understanding the 
origin or formation of parts of little importance; almost as great, 
though of a different kind, as in the case of the most perfect and 
complex organs,”’? and he devotes a section to a_ theoretical 
interpretation of them. Indeed he, on several occasions, recognises 
the existence of useless characters; ey., he says, “I am inclined to 
suspect that we see, at least in some of the polymorphic genera, 
variations which are of no service or disservice to the species; and, 
consequently, have not been seized on and rendered definite by 
natural selection.”* In this passage the word “ disservice” almost 
seems as if he had a suspicion that “injurious” characters might 
sometimes be present, though he elsewhere says :—‘“ Any actually 
injurious deviations in their structure would, of course, have been 
* «Origin of Species,” 6th ed., p. 175 ; see also p. 367. 
o ** Origin, etc.,” Pp. 156. 3 66 Origin, ete.,” p- 35. 
