ere is some approach, or at least some comparison to make
between vegetables and animals, this can only be by opposing plants
the most simply organized, like fungi and algae, to the most
imperfect animals like the polyps, and especially the amorphous
polyps, which occur in the lowest order.

"At present we clearly see that in order to bring about the
existence of animals of all the classes, of all the orders, and of
all the genera, nature has had to begin by giving existence to those
which are the most simple in organization and lacking most in organs
and faculties, the frailest in constituency, the most ephemeral, the
quickest and easiest to multiply; and we shall find in the
_amorphous_ or _microscopic polyps_ the most striking examples of
this simplification of organization, and the indication that it is
solely among them that occur the astonishing germs of animality.

"At present we only know the principal law of the organization, the
power of the exercise of the functions of life, the influence of the
movement of fluids in the supple parts of organic bodies, and the
power which the regenerations have of conserving the progress
acquired in the composition of organs.

"At present, finally, relying on numerous observations, seeing that
with the aid of much time, of changes in local circumstances, in
climates, and consequently in the habits of animals, the progression
in the complication of their organization and in the diversity of
their parts has gradually operated (_a du s'operer_) in a way that
all the animals now known have been successively formed such as we
now see them, it becomes possible to find the solution of the
following question:

"What is a _species_ among living beings?

"All those who have much to do with the study of natural history
know that naturalists at the present day are extremely embarrassed
in defining what they mean by the word species.

"In truth, observation for a long time has shown us, and shows us
still in a great number of cases, collections of individuals which
resemble each other so much in their organization and by the
_ensemble_ of their parts that we do not hesitate to regard these
collections of similar individuals as constituting so many species.

"From this consideration we call _species_ every collection of
individuals which are alike or almost so, and we remark that the
regeneration of these i