HYBRIDIZING. 
173 
attempts to effect a change are unavailing; they are altogether 
abortive, and of no more consequence than would be the applica¬ 
tion of any other foreign substance : hence then the necessity of 
removing at the earliest period the anthers of the flower to be 
impregnated, for should their pollen but once reach the stigma 
the opportunity is lost; generally the anthers may be extracted 
safely at the first opening of the blossom, though there are some 
plants with which the expansion of the flower and the ripening 
of the pollen are a simultaneous act, with such the anthers must 
be drawn from the bud, for so great is the volatility of the farina 
of most vegetation, that all certainty will be removed from the 
cross impregnation if that of the plant be allowed to ripen even 
on another flower at the same time, much less in such close 
proximity to the point of attention. 
Microscopic investigations show the action of the pollen in the 
fertilization of the seeds, to consist of the emission of certain tubes 
of the extremest tenuity through the stigma downwards by the 
style to the seat of the embryo seeds with which they come in 
contact; these tubes vary in number proportionately to the 
number of seeds contained in the pericarpium, and this fact 
will help to explain why there is or may be a difference in the 
produce of a single pod of seed when cross impregnation is 
resorted to. It is easy to suppose that some of tbtese filaments 
possess a different tenuity, or vital force, which may prevent their 
action in so forcible a degree as the remainder, which would of 
course have a considerable influence on the future plants, in all 
probability rendering them weaker than their fellows; while so 
far as stability of character is concerned, and the variations 
observable in this respect, they may be accounted for by sup¬ 
posing that only part of the seeds are fecundated by that 
particular pollen, and the remainder at a subsequent period by 
some of another kind. These are matters almost necessarily of 
conjecture, but there appears no better way in which to account 
for what we see, and this knowledge of the mode in which the 
pollen operates is sufficient to show us the almost physical im¬ 
possibility of superfoetation, for if the style be once filled with 
pollen tubes, by what means is any extraneous quantity to reach 
the seeds, even allowing there are any that have not received the 
impress of their future form. 
