PHYSIOLOGY, CHEMISTRY, AND MORPHOLOGY. 387 



isticof ;i living being by which energy is iiccumnhited and manifested, 

 transformed and given its s[)ecial developments. For these morpho- 

 logical facts express, as we have already said, elective activities slowly 

 accumulated iu the infinite past which, associating themselves with the 

 present chemical activities, give results that are unexpected iu i)ropor- 

 tion as we are ignorant of tlic intimate nature of the organization. 



Thus Pfefler,' after having observed that active bacilli are attracted 

 by peptone, l)y asparagine, by chloride of sodium, in short by many 

 substances, while the zoospores of ferns are attracted by malic acid, and 

 those of mosses by sugar of milk, and that the trillionthpartof a milli- 

 gram is sufficient to iiroduce that attraction, grants that the observer 

 might be led to conclude that there was here an act of volition rather 

 than a simple chemical phenomenon. Because of this and of many other 

 observations of a similar character, some authors regard the elective 

 action of molecular organisms as the rudimentary expression of tastes 

 and proclivities as Avell as the origin of certain idiosyncrasies and of 

 the more or less localized action of certain poisons, so that even in the 

 most simple phenomena of the nutritive activity of a tissue we encounter 

 a problem of selection indissolubly bound up with that of thought, the 

 origin of which is probably closely connected with that of life. 



To this may be added that not only do the chemical actions that 

 occur in an organism have a peculiar quality; the conditions under 

 which they occur are also special and peculiar to living beings — that is 

 to say, to organization and its products. We can indeed reproduce some 

 of these chemical processes that occur in the weft of our tissues, but to 

 obtain similar results we are obliged to employ very strong electric cur- 

 rents or reagents of such power that they would destroy any organism, 

 no matter what. In organized beings, on the contrary, these effects 

 are obtained at a temperature equal to or but a little above that of the 

 environment, at ordinary atmospheric pressure, under the influence of 

 currents so slight as to be hardly demonstrable, and by using chemical 

 affinities of the most feeble power. 



What we have said hitherto, while indicating the limits of jjliysiolog- 

 ical chemistry, detracts in no way from its great and real im})Ortance. 

 It is sufficient to mention the new spheres for investigation now o])eu- 

 ing — the metabolism of the tissues, the action of the blood glands, and of 

 the sympathetic nerve, auto- intoxication and immunity — to show how 

 vast is the field of practical action open to chemical research. It gives us 

 occasion to note how organisms in their manifold adaptations use these 

 affinities according to their varied conditions of existence, and how the 

 chemical forces adapt themselves to the production of colors, to the 

 distillation of perfumes, to the accumulation of substances, which, like 

 explosives, amass in small volume a large amount of virtual energy; to 

 the elaboration or materials of all kinds for the mechanical needs of 



'Pfeffer. "Ue I'irritabilite cbcz les jil-antes," ArcliiTas d«s s«ieuces physiques et 

 uaturelles, T. XXX, page 397, 1893. 



