430 
DARWINISM 
CHAP. 
of natural selection, but must be regarded as naturally trace¬ 
able to the vegetative checking of their respective types of 
leaf organ. Again, a detailed examination of spiny plants 
practically excludes the hypothesis of mammalian selection 
altogether, and shows spines to arise as an expression of the 
diminishing vegetativeness—in fact, the ebbing vitality of a 
species. 1 
Objections to the Theory. 
The theory here sketched out is enticing, and at first sight 
seems calculated to throw much light on the history of plant 
development; but on further consideration, it seems wanting- 
in definiteness, while it is beset with difficulties at every step. 
Take first the shortening of the raceme into the umbel and the 
capitulum, said to be caused by arrest of vegetative growth, 
due to the antagonism of reproduction. If this were the 
whole explanation of the phenomenon, we should expect the 
quantity of seed to increase as this vegetative growth dimin¬ 
ished, since the seed is the product of the reproductive energy 
of the plant, and its quantity the best measure of that energy. 
But is this the case ? The ranunculus has comparatively few 
seeds, and the flowers are not numerous; while in the same 
order the larkspur and the columbine have far more seeds as 
well as more flowers, but there is no shortening of the raceme 
or diminution of the foliage, although the flowers are large and 
complex. So, the extremely shortened and compressed flower- 
heads of the composite produce comparatively few seeds 
—one only to each flower; while the foxglove, with its long 
spike of showy flowers, produces an enormous number. 
Again, if the shortening of the central axis in the successive 
stages of hypogynous, perigynous, and epigynous flowers were an 
indication of preponderant reproduction and diminished vegeta¬ 
tion, we should find everywhere some clear indications of this 
fact. The plants with hypogynous flowers should, as a rule, 
have less seed and more vigorous and abundant foliage than 
those at the other extreme with epigynous flowers. But the 
1 This brief indication of Professor Geddes’s views is taken from the 
article “ Variation and Selection ” in the Encyclopaedia Britannica, and a paper 
“ On the Nature and Causes of Variation in Plants ” in Trans, and Proc. of the 
Edinburgh Botanical Society, 1886 ; and is, for the most part, expressed in 
his own words. 
