XIV 
FUNDAMENTAL PROBLEMS 
431 
hypogynous poppies, pinks, and St. John’s worts have abund¬ 
ance of seed and rather scanty foliage; while the epigynous 
dogwoods and honeysuckles have feAv seeds and abundant 
foliage. If, instead of the number of the seeds, we take the 
size of the fruit as an indication of reproductive energy, we find 
this at a maximum in the gourd family, yet their rapid and 
luxuriant growth shows no diminution of vegetative power. 
So that the statement that plant modifications proceed “ along 
an absolute groove of progressive change ” is contradicted by 
innumerable facts indicating advance and regression, improve¬ 
ment or degradation, according as the ever-changing environ¬ 
ment renders one form more advantageous than the other. 
As one instance I may mention the Anonacese or custard-apple 
tribe, which are certainly an advance from the Ranunculacese; 
yet in the genus Polyalthea the fruit consists of a number of 
separate carpels, each borne on a long stalk, as if reverting to 
the primitive stalked carpellary leaves. 
On the Origin of Spines. 
But perhaps the most extraordinary application of the 
theory is that which considers spines to be an indication of the 
“ ebbing vitality of a species,” and which excludes “ mammalian 
selection altogether.” If this were true, spines should occur 
mainly in feeble, rare, and dying-out species, instead of which 
we have the hawthorn, one of our most vigorous shrubs or trees, 
with abundant vitality and an extensive range over the whole 
Palaearctic region, showing that it is really a dominant species. 
In North America the numerous thorny species of Crataegus 
are equally vigorous, as are the false acacia (Robinia) and 
the honey-locust (Gleditschia). Neither have the numerous 
species of very spiny Acacias been noticed to be rarer or less 
vigorous than the unarmed kinds. 
On the other point—that spines are not due to mammalian 
selection—we are able to adduce what must be considered direct 
and conclusive evidence. For if spines, admittedly produced by 
aborted branches, petioles, or peduncles, are due soleh r or mainly 
to diminished vegetativeness or ebbing vitality, they ought to 
occur in all countries alike, or at all events in all whose similar 
conditions tend to check vegetation; whereas, if they are, 
solely or mainly, developed as a protection against the attacks 
