SELF-FERTILIZATION OF PLANTS. 321 
Lastly, Mr. Darwin’s expressions, “evil effects" and “injuriousness”’ of self-fertiliza- 
tion, seem to imply something of the nature of disease; but they show no consonance 
with Mr. Berkeley’s definition of disease, which is as follows :— 
* Tn all cases where the necessary functions of the species are impeded, and vital action is impaired, 
whether tending to actual decay or to the obstruction of the main ends of cultivation [aud I would 
add that the sole recognizable end of all plant-life in a state of nature is the propagation of the 
species by seed], we must assume that diseased action is going on” *. 
I hope this essay will clearly show that nothing of the kind can be predicated of the 
innumerable and habitually self-fertilized plants in nature. 
I will now state the nature of the observations which have led me to believe particular 
plants to be normally self-fertilizing (and by that I mean, though they may in some 
cases be cross-fertilized by insects, especially perhaps by small moths at night, yet there 
is every reason to believe such to be exceptional, and that they can and do fertilize 
themselves habitually) :— 
(a) Inconspicuousness of the flowers even when fully expanded. 
(b) Calyx and corolla, often only partially expanded, or not at all. 
(c) White or pale colour of the corolla; while specially coloured streaks, specks, or 
“ guides," Ee, are more or less reduced or absent. 
(d) Partial or total arrest of the corolla. 
(e) Little or no honey, though the disk or glands may be present. The glands found 
in allied species, however, may be suppressed in the self-fertilizing. 
(f) Little or no scent. 
(g) The mature stamens of the expanded flower retaining the incurved position they 
had in bud. ; 
(K) Stamens often reduced in number and the pollen in quantity. 
(i Pollen-tubes visibly penetrating the stigma, either from grains still within the 
anther-cells, or evidently derived from those of the same flower. 
(j) The stigma situated appropriately for direct pollinization from the anthers of the 
same flower. | 
(k) The order and rates of development of the different whorls, the pistil maturing 
with comparative rapidity. — | 
(1 The early maturation of the stigma so as to be ready before or simultaneously 
with the dehiscence of the anthers. 
(m) Great (absolute) abundance of fruit or seeds, or both. 
(n) Great rapidity of maturation of seed. [fertilization. 
(o) Special contrivances and adaptations of the stamens and pistil to secure self- 
(p) Cleistogamy. ` $ 
(q) Netting to exclude insects. 
(r) Growing them indoors and free from insect visits t. 
* « Vegetable Pathology,” Gard. Chron. (1854), p. 724. 
+ Of these two experimental methods (g and r) I have little experience, and am dependent upon Mr. Darwin's 
and H. Müllers observations. Having no facilities in London, I have been almost entirely compelled to forego 
these important methods. Still I venture to think that the cumulative evidence gathered under the preceding heads 
affords sufficient proof for conviction, which is quite equivalent to an absolute demonstration by such methods. 
