SELF-FERTILIZATION OF PLANTS. 345 
Next, selecting Alnus, the sexes are divided; but of the four sepals each has a stamen 
opposite to it. In Betula, the male flowers are heaped together in an irregular sort of 
manner; but still a stamen is in front of each sepal. In Populus, the limb of the calyx 
is now arrested, and we get a still further degradation, which culminates in Saliz*. 
The Cupulifere furnish another case of degradation, but from an offshoot from the 
Amentiferous genealogical tree. This group had originally advanced to a more highly 
differentiated state, as is proved by the inferior ovary; but here, again, the calyx of 
Quercus and Fagus, with stamens opposite to the sepals, indicates the same loss of a 
corolla, . 
If it be asked what is the evidence of the corolla having been totally arrested instead 
of its never having been formed, on the assumption that these were primitive types 
rather than degraded ones, the reply is that existing analogies seem to prove it. Thus 
we see the loss of it in members of the Alsinee, such as Sagina, Spergularia, &c., being 
both petalous and apetalous. In the latter condition the stamens opposite the petals 
disappear as well as the petals. They are the last to develop and are the first to go. 
Sueh (and many others might be quoted, where some species are apetalous, others 
petalous) would seem to support the idea that both a whorl of stamens and the corolla 
have been long lost in the case of the Amentiferee ; and in the Monochlamydez generally, 
wherever two whorls of stamens occur, as in Daphne, it seems to indicate the loss of 
the corolla only, while the different heights of the two staminal whorls in this plant 
may point to an ancestral heterostyled condition which perhaps no longer exists. 
I cannot therefore accept Mr. Darwin’s conclusion, that some plants “ have actually 
had their flowers reduced, and purposely rendered inconspicuous;" for I take it to be 
simply and purely, or at least mainly, a result consequent upon the absence of insects— 
just as, conversely, the conspicuousness of corollas, the development of secretive organs, 
dichogamy, and unisexuality are direct consequences of the disturbance in the floral 
equilibrium brought about by the actual visits of the insects themselves +. 
I think we should be very cautious not to confound means with ends. If I under- 
stand Mr. Darwin aright, he seems sometimes to look at the machinery for intercrossing 
as a purpose for benefiting the plant; elsewhere he shows and states clearly that inter- 
erossing per se does no good unless it bring constitutional differences; so that we must 
keep clear these two facts :—(1) The act of fertilization per se, as having its sole end the 
propagation by seed; (2) The constitutional benefits acquired through the agency of 
crossing. . 
With regard to the first, self-fertilization, as Mr. Darwin acknowledges, “is incom- 
parably the surest method ;” and for that purpose intercrossing is hazardous, if we do 
not use the word injurious. 
With regard to the second fact, it is clear that self-fertilization cannot introduce new 
* Authors regard the little prominence at the base of the stamens and of the pistil in Salix either as the calyx or 
‘else as the axis. It appears to me to be simply a cellular gland for secreting honey, which they do abundantly. 1 
could detect no spiral vessels in them at all. 
+ If we say that such structures appeared spontaneously, in anticipation, as it were, of the visits of insects, and 
so determined their coming, we at once fall into the old and objectionable teleological methods of interpretation. 
