20 Colonel David Bruce [Jan. 24, 



HoAv Does the Micrococcus Melitensis Leave 

 THE Body ? 



In regard to the first of these, it is conceivable that it might leave 

 the body by way of the expired air, in the saliva, in mucus from the 

 lungs, as in consumption, in the secretion of the skin, as in scarlet 

 fever, in the renal secretion, or by way of the intestinal tract. Or it 

 might leave the body by way of the blood, by the agency of mosqui- 

 toes or other biting flies. 



Many experiments were made along all these lines, and finally it 

 was decided that this micro-organism leaves the body principally in 

 the renal secretion, and in the blood taken out of the body by blood- 

 sucking insects. 



The result, therefore, of this experimental work was to give rise 

 to the belief that the disease was either conveyed from the sick to the 

 healthy by contact, or by inhalation of infected dust, or, lastly by the 

 agency of mosquitoes. 



How Does the Micrococcus Melitensis Gain Entrance 

 to the Body? 



The investigation of these various modes of infection was there- 

 fore undertaken. 



By Contact. — Let me first consider infection by contact. Experi- 

 ments were made by placing monkeys, one affected by Malta fever, 

 the other healthy, in more or less intimate contact, and it was found 

 that if the monkeys lived together in the same cage infection did take 

 place. If, on the other hand, the monkeys were kept in the same 

 cage, but separated by a wire screen, so that, although they could 

 touch each other, contamination of the healthy monkey's food by the 

 sick monkey could not take place, then infection did not take place. 



In regard to this question of conveyance by contact, there is one 

 argument against it which has always seemed to me unanswerable, 

 and that is, that thousands of cases of Malta fever have been invalided 

 home to England, and treated in our naval and military hospitals, 

 without, as far as I am aware, a single case of the fever arising among 

 the patients, orderlies, or nursing sisters. 



It was, therefore, concluded that contact with Malta fever patients, 

 or the handling of infected clothing or discharges, is not the mode of 

 infection. 



Then the question of infection by contaminated dust was taken up. 



By Dust Contaminated hy the Micrococcus Melitensis. — For some 

 time it was considered probable that this would prove to be the 

 common method of infection. The fact that the micrococcus with- 

 stands drying for a long time, the dusty nature of Malta, and the 



