Still, while rendering homage to the sentiment which induced Pasteur to efface himself in favour of Jenner, we may be permitted to say that there is no likeness between the two discoveries. Great as was the discovery of Jenner, it was but a chance observation, which had no ulterior development; and for a whole century, medicine has not been able to derive anything from it beyond its actual application, which is the one result achieved. 'Vaccination is vaccination,' an opponent of Pasteur's, who was driven hard, was obliged to say. The opponent found no other answer, and he could not have found any other. The cow-pox is a malady belonging exclusively to a race of animals. Man can only observe it; he cannot produce it. Suppress cow-pox and there will be no more vaccination. In the French discovery, on the contrary, it is the deadly virus itself which serves as a starting point for the vaccine. It is the hand of man which makes the vaccine, and this vaccine may be artificially prepared in the laboratory, in sufficient quantity to supply all needs. What a future is presented to the mind in the thought that the virus and its vaccines are a living species, and that in this species there are all sorts of varieties susceptible of being fixed by artificial cultivation! The genius of Jenner made a discovery, but Pasteur discovered a method of genius. 'This is but a beginning,' said M. Bouley on the day when Pasteur announced these facts to the Academy of Sciences. 'A new doctrine opens itself in medicine, and this doctrine appears to me powerful and luminous. A great future is preparing; I wait for it with the confidence of a believer and with the zeal of an enthusiast.' _THE VACCINE OF SPLENIC FEVER._