As far back as 1880, Schmidt-Mülheim[150] discovered that the injection of aqueous solutions of peptone into the blood-vessels of living dogs was attended by a series of remarkable phenomena. Thus, the animal passed at once into a condition of narcosis resembling that produced by chloroform, accompanied by a fall of general blood-pressure so great that the animal was liable to die, as from asphyxia. Further, there was evidence of some marked change in the condition of the blood, as indicated by loss of the power of spontaneous coagulation, while the peptone itself evidently underwent some alteration, or else was rapidly eliminated, since it could not be detected in the blood a short time after its introduction. These experiments, however, were not conducted with true peptone but with Witte’s “peptonum siccum,” which at that time, at least, was composed in great part of proteoses. The general character of these interesting results was confirmed by Fano,[151] who found that the injection of so-called peptone in the proportion of 0.3 gramme per kilo. of body-weight was sufficient to bring about complete narcosis, together with loss of coagulability on the part of the blood. Very suggestive, however, was the fact that Fano, on trying similar experiments with the peptone formed by pancreatic digestion, viz., with antipeptone, which presumably contained a far smaller proportion of proteoses, failed to obtain like results; the tryptone, so-called, being exceedingly irregular in its action, in many cases producing no effect whatever. [150] Beiträge zur Kenntniss des Peptons und seiner physiologischen Bedeutung. Du Bois-Reymond’s Archiv f. Physiol., 1880, p. 33. [151] Das Verhalten des Peptons und Tryptons gegen Blut und Lymphe. Ibid., 1881, p. 277.