SELF-FERTILIZATION OF PLANTS. 371 
then in their turn elongate, and so both stamens and pistil are of the same height and 
mature together. Moreover, instead of spreading out, the filaments are erect and parallel 
with the style, so that the anthers and stigmas are in contact. The corollas of the self- 
fertilizing species have all a tendency to remain only partially expanded; and as the 
anthers burst when in this condition, self-fertilization is secured. The extraordinary 
difference between the rapid development of the style in these species and its retardation 
in V. spicata, more especially the blue variety, is very curious. The fertilization is 
secured by bees and large Diptera visiting the flowers which have got their corollas; but 
in so doing they sweep their bodies over the long styles m project from the lower 
“ corollaless" flowers. ! 
Serophularia nodosa, with its small flowers, is proterogynous, and is “much frequented 
and fertilised by wasps” (Sir J. Lubbock, 7. c. p. 137). This fact is quite in keeping 
with the dwarfed size of the corolla, and moreover harmonizes with S. canina, dried 
specimens of which from Castleton, America, bore very small blossoms, of which the 
long style was much recurved, and had the stigma lying between the anthers. It 
had therefore all the appearance of being self-fertilized. The preceding was written 
before I found that Mr. T. Meehan had described it; for he thus speaks :— 
“ The pistil protruded while the anthers were’ still rolled back in the throat of the corolla. One by 
one the stamens were straightened out, the anther coming into close proximity with the stigma, when it 
burst, and by the contraction of the sacs the pollen was ejected, falling on to the stigma” (Proc. of Acad. 
of Nat. Sc. of Philadelphia, p. 13, 1876). 
The early growth of the pistil here mentioned quite corresponds with my general 
observations of self-fertilizing plants, and which have been several times alluded to. 
Linaria vulgaris. Mr. Darwin found this plant to be extremely sterile when covered 
up. I found some plants, in September 1876, with small spurred as well as spurless 
corollas. The pollen-tubes were penetrating the stigma from both the anthers above it 
as well as from below (Tab. XLIV. fig. 28); and Mr. C. B. Clarke informs me he has 
found similar aborted corollas, but of self-fertilizing flowers like the above, early in the 
season. Müller appears to infer that self-fertilization may take place at any time, from 
the relative positions of the essential organs, though Darwin's experiments do not, as 
stated, corroborate this. It may be, therefore, only in checked buds where self-fertiliza- 
tion occurs; for Müller alludes to this being the case with Scrophularia nodosa, which 
in warmer weather is fertilized by wasps; and he remarks that the capsules are just 
as replete with seeds from self-fertilization in cold and wet weather as by the aid of wasps 
when it is fine. The inference to be drawn is that self-fertilization was being attempted 
in correlation with the dwarfing and more or less arrested condition of the corolla, the 
two phenomena being so generally associated in plants which are habitually homo- 
gamous, 
L. minor. In this species the position of the stigma is also just between the anthers, 
and is. s abundantly self-fertilizing. 
Antirrhinum majus. Mr. Darwin records the fact that uncovered plants of the red 
e Kee of ES Sege bore more than twice the weight of seed as compared, with covered: | 
