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The Etiology of Scarlet Fever. 



[Mar. 3, 



from the latter source. The definite and clear proof that this is really 

 the case has now been obtained, and the evidence I now bring to the 

 notice of the Royal Society. 



On examining acute cases of human scarlatina — for which oppor- 

 tunity I owe great thanks to Dr. Sweeting, the Medical Superintendent 

 of the Fulham Fever Hospital — I soon ascertained the fact that there 

 is present in the blood of the general circulation a species of micro- 

 coccus, which on cultivation in nutritive gelatine, Agar- Agar mixture, 

 blood serum, and other media, proved to be in every respect identical 

 with that obtained from the Hendon cows. Out of eleven acute cases 

 of scarlet fever examined in this direction, four yielded positive results : 

 three were acute cases between the third and sixth day of illness 

 with high fever temperature, and the fourth was a case of death from 

 scarlatina on the sixth day. In all these four cases several drops of 

 blood were used, after the customary methods and under the required 

 precautions for establishing cultivations in a series of tubes con- 

 taining sterilised nutritive gelatine, and generally only a very small 

 number of these tubes revealed after an incubation of several days 

 one or two colonies of the micrococcus. This shows that the micro- 

 cocci were present in the blood in but small numbers. 



Having ascertained the identity in morphological and cultural 

 respects of the micrococcus of the blood of human scarlatina with the 

 organism obtained from the Hendon cows, the action of the cultiva- 

 tions of both these sets of micrococci was then tested on animals and 

 the results compared. It was found that mice — wild mice better 

 than tame ones — on inoculation as well as feeding, became affected 

 in exactly the same manner, no matter whether the one set of 

 cultivations or the other was used. The great majority of these 

 animals died after between seven and twenty days ; the post-mortem 

 examination revealed great congestion of the lungs, amounting in 

 some cases to consolidation of portions of the organ, congestion of 

 the liver, congestion and swelling of the spleen, great congestion and 

 general disease of the cortical part of the kidney. From the blood 

 of these animals, taken directly from the heart, cultivations were 

 established in nutritive gelatine, and hereby the existence of the 

 same species of micrococci was revealed ; they possessed all those 

 special characters distinguishing the cultivations of the micrococcus 

 of the Hendon cows and of the human scarlatina. 



In the third and concluding section of the work, cultivations of the 

 micrococcus of two cases of human scarlatina were used for infecting 

 calves ; two calves were inoculated and two were fed from each set 

 of cultivations. All eight animals developed disease, both cutaneous 

 and visceral, identical to that produced in the calves that had been 

 last year infected with the micrococcus from the Hendon cows. 



From the heart's blood of calves thus infected from human 



