INFECTION 253 



Has the specific germ of diphtheria any property to war- 

 rant such a view? If a fluid culture of bacillus diphtheriae 

 be filtered through a porcelain filter, the filtrate will contain 

 none of the bacteria. If this filtrate, free of all bacteria, 

 be injected into animals, death ensues; and if the tissues of 

 these animals be examined, all of the most important lesions 

 that characterized the tissues of the animal dead after 

 inoculation with the living germ are to be found. 



If a parallel experiment be made with the bacillus of 

 tetanus analogous results will be obtained. 



It is clear, then, that here are two species of bacteria that 

 excite the characteristic results through the instrumentality 

 of a something that they manufacture in the course of their 

 growth; that may be separated from them by the simple 

 process of filtration, and that when so separated possesses 

 all the properties of specific intoxicants. 



In anthrax and other septicemias we saw that, normally, 

 the infection was characterized by the distribution of the 

 bacteria throughout the body, but that modified results, 

 differing only in degree, might still be obtained with the 

 attenuated organisms without such general distribution. 

 These latter conditions must, therefore, have been caused 

 by a poison elaborated by or escaping from the locally 

 deposited organisms and carried to distant parts of the body 

 by the circulating fluids. In tuberculosis the nodules result- 

 ing from inoculation with the dead bacteria must have been 

 the result of a poison associated with the bodies of those 

 dead bacteria and liberated with their disintegration in the 

 tissues; while in diphtheria it is plain that its characteristic 

 manifestations are the outcome of a poison produced locally 

 by the growing bacteria and carried thence by the circulating 

 fluids to distant organs, there to exhibit its destructive 

 properties. 



