PLAGUE, RATS AND FLEAS. 263 



and other adverse circumstances in uncongenial surroundings. While 

 other non-spore-bearing bacteria readily perish when removed from 

 their natural soil. The more resistant germs which do not produce 

 spores have a protective wall which shields their internal contents. 



The Bacillus mallei is a fairly resistant non-spore bearing germ. We 

 should expect, therefore, glanders to he a disease which might be 

 capable of transference from diseased animals, by various agents, to 

 healthy animals ; but the period of the vitality of the bacillus outside 

 the bcdy of an animal would be short, compared with the period of 

 vitality of the spore-bearing anthrax bacillus. And this is precisely 

 what we do find. Thus, we have such cases recorded as that of a 

 woman who developed glanders three days after washing the clothes of 

 a man who had died of the disease, or a case of a person who acquired 

 the disease by heing struck by the fist of a man who owned a glandered 

 horse. Generally, however, the infection is more direct from the sick 

 horse to man. 



When we come to hydrophobia, we find that in order to produce the 

 disease, infection must always he obtained direct from the diseased 

 animal to the healthy, — generally by its bite. The germ is incapable 

 of existing for any time outside the animal body. 



Now, the plague germ does not bear spores ; hence it cannot remain 

 alive for a long period exposed to air and light and other adverse 

 agencies, in the way the anthrax bacillus does. Nor yet has the plague 

 germ any resistant cell-wall. Plague is certainly not conveyed to man 

 by direct inoculation as hydrophobia is. How, then, can we explain the 

 infection of man from the rat ? 



A little further thought on the methods of reproducing plants adopted 

 by the mali will enable us perhaps to solve the problem. Has he any 

 other method of making cuttings? Of course, there is the method of 

 making a gooty. He selects a certain part of the plant, and ties around 

 it some moss and earth which he keeps constantly moist. Many plants 

 which could only be propagated by means of cuttings with difficulty 

 can thus easily be reproduced. Have we anything analogous to the 

 gooty in the case of plague? I believe the flea is the gooty. The 

 plague germs which abundantly circulate in the blood in the final stage 

 of the disease are taken up along with the blood by the flea. I show 

 you a specimen under the microscope which is a section through the 

 stomach of a flea. This flea was fed on a plague-sick rat, and allowed 



