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 between the phenomena of the two orders to the manner of their occurrence, seem to admit the complete identity of the mechanisms. It is no longer then in itself, individually, that the vital act is particularized, but in the manner in which it is linked to others. The vital order is a series of physico-chemical acts realizing an ideal plan.

Neo-vitalism has therefore assumed two forms, one the more scientific and the other the more philosophical.

''Chr. Bohr and Heidenhain.''—Its scientific form was given to it by Chr. Bohr, an able physiologist at Copenhagen, and by Heidenhain, a professor at Breslau, who was one of the lights of contemporary German physiology. The course of their researches led these two experimentalists, working independently, to submit to fresh investigation the ideas of Lavoisier and those of Bichat, on the relation of physico-chemical forces to the vital forces.

It was by no means a question of a general inquiry, deliberately instituted with the object of discovering the part played respectively by physical and physiological factors in the performance of the various functions. Such an investigation would have taken several generations to complete. No; the question had only come up incidentally. Chr. Bohr had studied with the utmost care the gaseous exchanges which take place between the air and the blood in the lungs. The gaseous mixture and the liquid blood are face to face; they are separated by thin membrane formed of living cells. Will this membrane behave as an inert membrane deprived of vitality, and therefore obeying the physical laws of the diffusion of gases? Well! no. It does not so behave. The most careful