THE BUBONIC PLAGUE. 71 



ing into the presence of tlie sick one, while the truth is he may- 

 carry the germ under his finger nails or elsewhere about him, and 

 there is no telling when it may first find its way into his body. 

 We can determine the period of incubation in the lower animals 

 by inoculation, and here we know that it varies greatly with the 

 method of inoculation, the virulence of the germ, the number of 

 germs introduced, and the susceptibility of the animal. All that 

 may be said about the period of incubation in man is of but little 

 value. The same is largely true concerning the extent to which 

 the disease is contagious. In the epidemic of 1835 in Egypt only 

 one of the French physicians who attended the sick contracted 

 the disease. Bulard, who did not believe the plague contagious, 

 wore for two days a shirt taken from the body of a dead man. 

 He remained well, and thought that by this he had demonstrated 

 the truth of his theory. Such experiments demonstrate nothing. 

 There is no evidence that any of the bacilli were on the garment, 

 or that, if they were, they were introduced into his body. During 

 the epidemic in Hong Kong, fifteen European physicians and a 

 number of Chinese medical students cared for the sick in the hos- 

 pital, and none acquired the disease. This only shows that with 

 care and cleanliness the sick may be attended without danger of 

 infection of the attendants. Hundreds of bacteriologists in labo- 

 ratories are daily handling the most virulent cultures of the diph- 

 theria bacillus, and the first case of infection from this source has 

 yet to be reported. This does not prove that these bacilli are not 

 pathogenic to man, or that these men are insusceptible to the dis- 

 ease. Because an expert handles the most venomous serpents 

 without being bitten, does not prove that the bite of these reptiles 

 is harmless. 



The exaggerated idea of the contagiousness of the plague held 

 by some of the older writers is exemplified in a graphic way by 

 the following quotation from Hecker : "Every spot which the 

 sick had touched, their breath, their clothes, spread the conta- 

 gion ; and, as in all other places, the attendants and friends who 

 were either blind to their danger or heroically despised it, fell a 

 sacrifice to their sympathy. Even the eyes of the patient were 

 considered as a source of contagion which had the power of act- 

 ing at a distance, whether on account of their unwonted luster or 

 the distortion which they always suffer in plague, or whether in 

 conformity with an ancient notion, according to which the sight 

 was considered as the bearer of demoniacal enchantment.'' 



The plagues of the middle ages were undoubtedly spread by 

 the processions of the Brotherhood of the Cross. These fanatics 

 went, sometimes in great numbers, from place to place, praying 

 for the sins of the world, and scourging themselves with leathern 

 straps armed with points of iron. 



