s on or unites with the germ, are
questions which cannot be answered with any certainty. It is, however,
possible that both sexual elements perish, unless brought into union,
simply from including too little formative matter for independent existence
and development; for certainly they do not in ordinary cases differ in
their power of giving character to the embryo. This view of the importance
of the quantity of formative matter seems probable from the following
considerations. There is no reason to suspect that the spermatozoa or
pollen-grains of the same individual animal or plant differ from each
other; yet Quatrefages has shown in the case of the Teredo,[881] as did
formerly Prevost and Dumas with other animals, that more than one
spermatozoon is requisite to fertilise an ovule. This has likewise been
clearly proved by Newport,[882] who adds the important fact, established by
numerous experiments, that, when a very small number of spermatozoa are
applied to the ova of Batrachians, they are only partially impregnated and
the embryo is never fully developed: the first step, however, towards
development, namely, the partial segmentation of the yelk, does occur to a
greater or less extent, but is never completed up to granulation. The rate
of the segmentation is likewise determined by the number of the
spermatozoa. With respect to plants, nearly the same results were obtained
by Koelreuter and Gaertner. This last careful observer found,[883] after
making successive trials on a Malva with more and more pollen-grains, that
even thirty grains did not fertilise a single seed; but when forty grains
were applied to the {364} stigma, a few seeds of small size were formed.
The pollen-grains of Mirabilis are extraordinarily large, and the ovarium
contains only a single ovule; and these circumstances led Naudin[884] to
make the following interesting experiments: a flower was fertilised by
three grains and succeeded perfectly; twelve flowers were fertilised by two
grains, and seventeen flowers by a single grain, and of these one flower
alone in each lot perfected its seed; and it deserves especial notice that
the plants produced by these two seeds never attained their proper
dimensions, and bore flowers of remarkably small size. From these facts we
clearly see that the quantity of the peculiar formative matter which is
contained within the spermatozoa and pollen-grains is an all-important
element in the act of fertilisation, not only