The story of the discovery of the germ of a disease which has destroyed thousands, perhaps millions, of human lives, is a matter of considerable interest and certainly vastly more important than that of a king who has conquered nations. And if this discovery is supplemented by a remedy which will cure or prevent the disease, it will surely be one of the greatest blessings which the world has ever known. Both of these attainments seem to be within the grasp of Dr. Sanarelli. During the early part of the present year (1897) he discovered the little organism which is the cause of the yellow pest. The news has spread over the entire world, but with the usual conservative attitude of the medical profession the brilliant discovery has been but slowly recognised; even at present there are many doubters who will not accept the newly discovered organism as the sole cause of yellow fever until confirmatory observations establish the fact more definitely. The Montevideo doctors, however, one and all, accept the discovery as final and look with confidence to Dr. Sanarelli for the practical outcome of the curative plan of treatment upon which he is now experimenting. To cure yellow fever with its cause in hand, it is proposed to make a fluid similar to the anti-diphtheritic serums, which are either destructive or inhibitory to the germs in question. Such a serum has been made and it has been tried upon beasts and men with what Dr. Sanarelli considers marked success. The Brazilian government, in whose domain there is always a nursery of the disease, has recognised the great possibilities of this work, and will shortly set up an experimental laboratory for the manufacture of the serum. For a positive judgment as to the success or failure of the serum plan of treatment we must wait for a long trial, perhaps several years; but the glory and the credit of being the first to see in this dangerous little speck of life, hitherto invisible, an enemy which has caused the death of uncounted thousands of vigorous human lives, already belongs beyond a question to Dr. Sanarelli.