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The worthy Abbe Spallanzani must have known some such when he saw pieces of raw meat begin to run under the action of the gastric juice which he took, with pellets of sponge, from the stomachs of crows. He discovered the secrets of digestion; he realized in a glass tube the hitherto unknown labors of gastric chemistry.
His initial experiments were made in 1777, and from the outset the problem was as good as solved. Other experimenters confirmed his results in all their essentials notably Scheele and Lavoisier and Spallanzani and Davy.
Cut off the legs, the tail, the jaws, separately or all together, and, as Spallanzani showed long ago, these parts not only grow again, but the reintegrated limb is formed on the same type as those which were lost. The new jaw, or leg, is a newt's, and never by any accident more like that of a frog.
Spallanzani kept several frogs in the center of a lump of ice for two years, and, although they became dry, rigid, almost friable, and gave no external appearance of being alive, it was only necessary to expose them to a gradual and moderate heat to put an end to the lethargic state in which they lay.
Let it suffice to say that they were on the lines first laid down by Redi and greatly elaborated by Spallanzani, namely the exclusion from the fluids or other substances under examination of all possible contamination by minute organisms in the air. Spallanzani knew nothing of these organisms; they were not discovered until many years after his death.
Spallanzani ascertained the perfection of this faculty by a series of cruel experiments, by which he demonstrated that bats, even after their eyes had been destroyed, and their external organs, of smell and hearing obliterated, were still enabled to direct their flight with unhesitating confidence, avoiding even threads suspended to intercept them.
Among the most interesting researches of Spallanzani were his experiments to prove that digestion, as carried on in the stomach, is a chemical process. In this he demonstrated, as Rene Reaumur had attempted to demonstrate, that digestion could be carried on outside the walls of the stomach as an ordinary chemical reaction, using the gastric juice as the reagent for performing the experiment.
He believed in reversing original propensities by education, as Spallanzani brought up eagles on bread and milk, and fed doves on raw meat. "Don't let us demand too much of human nature," was a line in his creed; and he believed in Hood's advice, that gentleness in a case of wrong direction is always better than vituperation.
His experiments still hold the field in a region of study which has vastly extended itself in recent years, becoming of prime importance in the vitalistic controversy. In the dispute, however, with which we are concerned Needham and Spallanzani defended opposite positions.
The result was discoverable, he added, in that silent, yet importunate and terrible influence which for centuries had moulded the destinies of his family, and which made him what I now saw him what he was. Such opinions need no comment, and I will make none. * Watson, Dr. Percival, Spallanzani, and especially the Bishop of Landaff. See "Chemical Essays," vol v.
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