DR DENNY ON RELATIVE INFLUENCE OF PARENTAGE. 23 
section, save with one another ; and, showing the existence of 
affinity between what are supposed to be distinct species, I have 
fertilised without much difficulty a variety {peltatum elegans) of the 
Ivy-leaved section by the pollen of the zonal. 
I have also alluded to the possible difference in the respective 
influence of the parents in true hybridisation. Upon this point I 
have not sufficient evidence to form a fair opinion ; but certainly in 
the seedlings I have raised between the Ivy-leaved and the zonal 
sections, their foliage (with the exception of some distinctive 
evidence of their being hybrids) resembles almost entirely that of 
their mother, which it will be observed is the reverse of my expe- 
rience of the results produced between varieties. 
Much has been written and said upon the difference in the 
quality and powers of the pollen of the short stamens, and if the 
supposed difference really does exist, it is a matter of considerable 
practical importance, and one worthy of further scientific investiga- 
tion ; but my experiments have hitherto failed to satisfy me of 
their possessing any difference. In an admirable article upon 
hybridisation, written by Isaac Anderson-Henry, Esq. (and which 
at different periods has appeared in nearly all the horticultural 
journals), he says " that, owing to the granules of the short 
stamens being smaller than those of the long ones, they can the 
more easily descend the tubules leading from the stigma to the 
ovaries, and consequently facilitate the crossing of a large-flowered 
variety, or species, upon a smaller one." I have not been able to 
detect this difference in size, although I have many times placed 
the granules of the long and short stamens side by side under a 
powerful microscope ; nor, I believe, is it the opinion of physio- 
logists of the present day that they do descend these tubules at all 
— in fact, it has been shown that they send down filaments through 
them to the ovules. 
The arrangement of the anthers upon filaments of different 
lengths looks to me like a provision to ensure all parts of the body 
and legs of the insect coming into contact with the pollen as it 
passes down the flower to obtain the nectar, thereby rendering the 
fertilisation of the next flower it visits the more certain. 
The visible effects of impregnation are frequently manifested 
with a rapidity almost equalling that of an electrical phenomenon. 
I have observed the petals of the Pelargonium, which, before im- 
pregnation, were quite firm, to fall within a few seconds of the 
application of the pollen to the stigma — a result due, I conclude, 
either to the immediate diversion of nourishment from the then 
