ANTHRAX AND ANTHRACOID DISEASES. 149 



being taken by a long row of seeds or spores. Koch concluded 

 that these spores, as distinguished from the rods, constituted 

 the contagium of the disease in its most deadly and persistent 

 form. 



By inoculating animals with the fresh blood of an animal 

 suffering from splenic fever, he found that they invariably died 

 within twenty to thirty hours after inoculation. By drying the 

 infectious blood containing the rod-like organisms, in which, 

 however, the spores were not developed, he found the contagion 

 to be fugitive, maintaining its power of infection for five weeks 

 at the furthest. He then dried the blood containing the fully- 

 developed spores, and exposed it to a variety of conditions. 

 He permitted the dried blood to assume the form of dust, 

 wetted this dust, allowed it to dry again, placed it for an 

 indefinite period in the midst of putrefying matter, and 

 subjected it to other tests. After keeping- this spore-charged 

 blood, which had been treated in this fashion for four years, 

 he inoculated a number of mice with it, and found its action 

 as fatal as that of blood fresh drawn from the veins of an 

 animal suffering from splenic fever, each spore in the millions 

 contained in the diseased blood being sufficient to produce the 

 disease. 



The bacilli are not always found in the blood of living animals 

 suffering from the disease ; indeed, they generally appear a few 

 hours before death (which seldom takes place in less than twenty 

 hours), and then only singly and in very small numbers. Even 

 after death they cannot always be found in the blood, but always 

 in the spleen. Their number, however, varies with the animal 

 inoculated ; in the guinea-pig they are numerous, sometimes 

 exceeding the blood corpuscles ; in the rabbit much smaller, 

 and in the mouse often absent altogether. If the disease has 

 been induced by inoculation, they are present, though in 

 variable numbers, in the inoculation carbuncle. Though the 

 rods are not always found in the blood, the spores are said to 

 be invariably present, and some assert that it is their product 

 that destroys life. 



The bacilli rods, as found in the blood and spleen, vary in 

 length very considerably, those in the spleen being longer, the 

 shortest rods being in length generally about twice the diameter 

 of a human red corpuscle, the longer ones two or three times 

 the length of the shorter ; but when carefully examined, the 

 latter will be seen in a process of division into two or more 

 segments. According to the observations of Koch, it appears 

 that, whatever be the species of animal inoculated with anthrax 

 blood, and no matter how many successive inoculations may be 

 made, the bacilli multiply solely by fission, but only so long 

 as the animal is alive ; when dead a minute portion of its blood, 



