This last experiment naturally brings to remembrance those of Dr. Home at Edinburgh, in which he inoculated the measles by means of the blood of patients ill of that disorder. From the accounts he has given in his treatise entitled Medical Facts and Observations, we can have little doubt that _his_ experiments succeeded, however others may have failed. One thing, however, is very obvious, viz. that if we mean to communicate a disease by means of the blood, we must use a much greater quantity than if we make the experiment with the matter of an abscess. The case of contagious diseases seems to be the same as in fermenting liquors. With a small quantity of yeast we can easily induce fermentation in any proper liquor, but, if we skim off the yeast, and use only the pure fermenting liquor, we must use a much greater quantity; and to inattention to this circumstance we may with probability ascribe the difficulty which Dr. Home himself met with in introducing the disease, and the total want of success in others. In M. Couzier’s experiment a considerable quantity must have been used, as he says that in the dog’s stomach it equalled the size of an hen’s egg. A much smaller quantity of matter taken from a pestilential abscess is capable of producing the disease in a human body, as is evident from the case formerly quoted of that gentleman who inoculated himself for the plague, and of which Dr. Guthrie gives the following account: “This was Mathias Degio, one of the surgeons of the hospital at Bucharest, a building appropriated to the cure of the plague in the Russian army. He, perceiving the gentlemen of his profession _condemned in a manner to death, if punctual in the discharge of their duty_[103] had the resolution to inoculate himself for the plague, in the full confidence of its efficacy, and ever afterwards found himself invulnerable, whilst his companions around him were falling victims to its fury. He produced the disease by inserting, with the point of a lancet, under the epidermis of his arm, matter from a pestiferous abscess, and followed the cold regimen observed in the small-pox, as he had imitated its mode of inoculation. On the fourth day of the puncture the fever declared itself, and he, being perfectly devoid of fear, got through the disease without feeling more inconvenience than if it had been that which he imitated. He drank freely of cold water, with vinegar, or a little wine, and kept generally out of doors. This beverage was the only thing that had the appearance of medicine,” &c. [103] This, among innumerable other instances that might be brought, is a proof of the infectious nature of the plague.