ss the internal disposition of its parts, and
rendering it suitable to continually absorb and to exhale the other
environing fluids which are able to penetrate into its interior, and
which are susceptible of being contained.

"These other fluids, which are water charged with dissolved
(_dissous_) gas, or with other tenuous substances, the atmospheric
air, which contains water, etc., I call containable fluids, to
distinguish them from subtile fluids, such as caloric, electricity,
etc., which no known bodies are believed to contain.

"The containable fluids absorbed by the small gelatinous mass in
question remain almost motionless in its different parts, because
the non-containable subtile fluids which always penetrate there do
not permit it.

"In this way the uncontainable fluids at first mark out the first
traces of the simplest organization, and consequently the
containable fluids by their movements and their other influences
develop it, and with time and all the favorable circumstances
complete it."

This is certainly a sufficiently vague and unsatisfactory theory of
spontaneous generation. This sort of guess-work and hypothetical
reasoning is not entirely confined to Lamarck's time. Have we not, even
a century later, examples among some of our biologists, and very eminent
ones, of whole volumes of _a priori_ theorizing and reasoning, with
scarcely a single new fact to serve as a foundation? And yet this is an
age of laboratories, of experimentations and of trained observers. The
best of us indulge in far-fetched hypotheses, such as pangenesis,
panmixia, the existence of determinants, and if this be so should we not
excuse Lamarck, who gave so many years to close observation in
systematic botany and zooelogy, for his flights into the empyrean of
subtle fluids, containable and uncontainable, and for his invocation of
an _aura vitalis_, at a time when the world of demonstrated facts in
modern biology was undiscovered and its existence unsuspected?

_The Preexistence of Germs and the Encasement Theory._--Lamarck did not
believe in Bonnet's idea of the "preexistence of germs." He asks whether
there is any foundation for the notion that germs "successively develop
in generations, _i.e._ in the multiplication of individuals for the
preservation of species," and says:

"I am not inclined to believe it if this preexistence is taken in a
general sense; but in limiting it to individu