"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 _à 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 zoölogy, 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 Preëxistence of Germs and the Encasement Theory._--Lamarck did not believe in Bonnet's idea of the "preëxistence 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 preëxistence is taken in a general sense; but in limiting it to individuals in which the unfertilized embryos or germs are formed before generation. I then believe that it has some foundation.--They say with good reason," he adds, "that every living being originates from an egg.... But the eggs being the envelope of every kind of germ, they preëxist in the individuals which produce them, before fertilization has vivified them. The seeds of plants (which are vegetable eggs) actually exist in the ovaries of flowers before the fertilization of these ovaries."[112]