ETIOLOGY— CAUSES OF DISEASE 227 



used when the length of the rod is more than twice its diameter. There 

 are also other forms, distinguished by the terms vibrios and spirilla (fig. 

 75), and other filamentous forms. 



Action of bacteria in the production of disease.— When it 



was first suggested that diseases were due to the action of minute 

 organisms, the question as to the mode of their action naturally arose, 

 and various theories were promulgated. Some authorities were disposed 

 to refer the deleterious influence of the microbes to the mechanical 

 blocking-up of the vessels by accumulation of large numbers. This view, 

 however, was obviously insufficient to account for the phenomena which 

 were observed. A more reasonable view refers their baneful effects to a 

 fermentative process which it would appear to be their particular function 

 to originate. Some experiments which were made with reference to septic 

 infection by Dr. Hiller went far to prove that the bacteria themselves were 

 perfectly harmless, but were capable of inducing chemical 

 changes in the fluids and solids of the body which led 

 to the formation of animal poisons. Dr. Burdon San- 

 derson, in commenting on this function of bacteria, 

 and particularly on Dr. Hiller's experiments, remarks 

 that having collected a considerable mass of bacterial 

 material, that is, of bacteria obtained from various 

 fluids in advanced putrefaction, on a filter, Dr. Hiller 

 washed the mass, just as one washes a precipitate, a 

 great number of times; then diffused the material 

 which had been so washed in distilled water, and in- B Spirillum „ ncUlla 

 jected it in repeated doses into the circulating blood ' chromatic granules. 

 of animals. The injections were entirely without effect. 3 Protopks°m eS ' 

 Hiller next proceeded to inoculate himself with the c.spMiumrubrumwith 

 same material, and again without effect. The advocates 

 of bacteria at once objected to Hiller's experiment that the bacteria, not 

 being accustomed to distilled water, were so injured by the repeated 

 washings that they had lost their activity. The criticism, however, might 

 just as well have been spared, for it afforded Hiller the opportunity of 

 proving by experiment, which was, of course, easy enough, that the 

 washed bacteria were as lively and as capable of development as ever. 

 It would appear from these observations as to the function of bacteria in 

 the production of septic infection that they are really manufacturers of 

 poison, and that when freed themselves from the material in which they 

 live they are perfectly innocent. This view, which was promulgated ten 

 years ago, is the one which is in favour with advanced pathologists, and 

 it is a remarkable development of Dr. Hiller's researches that bacteria 



