THE GERM THEORY OF DISEASE. YELLOW FEVER. 337 
THE GERM THEORY OF DISEASE. 
T the meeting of the British Association, held at Southport in 
A September last, Dr. Carpenter read a paper on the germ theory 
of disease. Notwithstanding the tendency among modern patholo- 
gists to regard the various forms of zymotic disease as distinct, he 
maintained that. the application of the natural history method to 
the study of these diseases justified the belief that the same germs, 
undergoing development under different conditions, manifested 
themselves in a great variety of forms ; that scarlatina, small-pox, 
and other diseases of this nature had acquired considerable fixity 
of type, yet that this fixity did not necessarily hold good over the 
whole world, or for all time. Inoculation for small-pox did this 
great good, that it cultivated a mild disease out of a severe one, 
as was proved during the plague in the middle of last century. 
A converse result was observed during the siege of Paris in 1870, 
when malignant small-pox developed from the mild form of the 
disease ; the epidemic broke out violently in London, and extended 
over the whole kingdom. Further, he argued that malarial disease 
originating in germs bred in the soil was convertible into a dis- 
tinct form of disease, into germs which bred in the human body, 
and could be communicated from one human body to another. 
The same doctrine held true in regard to typhus and typhoid 
fever—an opinion in which he was supported by the late Sir 
Robert Christison. Lately he had a controversy with Dr. Tyndall 
on this subject, Dr. Tyndall holding that cholera could only be 
propagated by germs from the human body. ‘The speaker on the 
other hand maintained that the germs might be bred in collec- 
tions of decomposing matter, sewers, heaps of filth, and marshes. 
This view was supported by the report just published by Surgeon- 
General Hunter on the recent epidemic of cholera in Egyyt. Dr. 
Hunter had completely disproved the theory that the disease had 
been imported from India, and shown that it had originated from 
the Egyptian marshes. 
YELLOW FEVER. 
R. DOMINGOS FREIRE, of whose alleged discovery of the 
micro-coccus of yellow fever we gave an account some time 
ago, has, according to a communication from his own pen which 
appears in the Brazilian papers, already begun to ‘‘vaccinate” 
human beings resident in Brazil, in order to protect them against 
the dreaded South American scourge. It will be remembered that 
