fusion of the substance of the sperm
filament with that of the egg in such a way that there is a distinct
and intimate fusion of the nucleus of the sperm filament with the
nucleus of the egg-cell. The recent discovery of M. Bataillon is this,
viz. that you can make the frog's egg develop in a perfectly regular
way and become a tadpole and then a young frog without the admission
to it of a sperm-filament or of any substance derived from the male
frog. All you have to do--and the operation, though it sounds easy and
simple, is an exceedingly delicate and difficult one--is to prick with
a fine needle the surface of the little black egg-sphere (not merely
of the jelly surrounding it) when it is shed by the female frog into
perfectly pure water free from sperms or anything of the sort. The
slight artificial puncture acts as does the natural puncture by the
swimming sperm-filament, and is sufficient! The egg proceeds to
develop quite regularly. There is no fusion of the nucleus of the
egg-cell with any matter from the outside; no paternal "material" is
introduced, but the nucleus of the egg-cell divides just as though
there had been! The whole progeny of cells, successively formed, are
the pure offspring of the maternal egg-cell and its nucleus. The
tadpoles and young frogs so produced are examples of what is called
"parthenogenesis"--that is to say, virginal reproduction--reproduction
without fertilisation by material derived from a male parent! The
needle, which gives off no material, but simply makes a tiny break in
the surface of the egg, does all that is necessary!

To those not acquainted with all that has been ascertained as to the
reproduction of lower animals such as insects, crustaceans, and worms,
this discovery will appear more astonishing than it really is. We
know of many lower animals in which the egg-cells produced by the
females do regularly and naturally develop without the intervention of
a male and without fertilisation. In an earlier volume[7] of this
"Easy Chair Series" I wrote of this curious subject, and described the
virgin reproduction or parthenogenesis of the hop-louse and
other plant lice, of some moths, of some fresh-water shrimps,
and of the queen bee (who produces only drones by eggs which are
not fertilised). But I had to point out then that no case was known of
"parthenogenesis"--that is to say, reproduction by unfertilised
eggs--among the whole series of vertebrate animals, the fishes,
amp