206 TEXT-BOOK OF BACTERIOLOGY. 



as a rule spores are formed in great number at a suitable tem- 

 perature. 



The list of substances able to furnish the anthrax bacilli the 

 necessary conditions for undisturbed growth is not yet Toy any 

 means exhausted. The most widely-differing substances, chiefly of a 

 vegetable nature, it is true, are able to yield sufficient nutriment, 

 and infusions of hay or pea-straw, seeds of all kinds which contain 

 starch, flour, wheat especially, and also turnips, etc., satisfy the 

 appetite of this bacillus, which is not very dainty. 



Although after what has been said it may not seem sufficiently 

 clear that the anthrax bacillus is not specially formed for a par- 

 asitic existence, yet this view will be corroborated by a very simple 

 consideration. It will be remembered that we regarded the forma- 

 tion of spores as the expression of the culmination of development 

 in a micro-organism; it is at any rate a very important, almost 

 indispensable, part of its development. But the anthrax bacillus 

 forms its spores only outside the bodies of animals, and we may, 

 therefore, conclude that it is originally a genuine saprophytic spe- 

 cies, which indeed can occasionally make an excursion into foreign 

 regions, but must return to its proper home to obtain its maximum 

 development. 



For us, indeed, the parasitic existence of these bacilli is particu- 

 larly interesting and important, since it is here that they display 

 their pathogenic qualities. The anthrax bacillus is one of the most 

 infectious species known to us. The very smallest portion of a 

 healthy culture, suitably inoculated into a susceptible animal, suf- 

 fices with certainty and under all circumstances to produce splenic 

 fever, and as a rule to cause death. 



The entrance of the bacteria into the body may take place by 

 any of the ways which are open to the micro-organisms, and there 

 is no definite mode of infection to which the anthrax bacillus is 

 limited. 



Thus it may enter through slight injuries to the skin, by inocula- 

 tion, or by^ subcutaneous application. In this so-called wound an- 

 thrax or inoculation anthrax the bacteria spread chiefly by way of 

 the blood; a simple cell may increase to many millions and so over- 

 run the entire organism. The affection is characterized as a genu- 

 ine septicaemia, and the post-mortem state of the body confirms 

 this view. 



After inoculation of a Guinea-pig with anthrax, the vicinity of 

 the place of inoculation is almost unaltered as a rule. Only in rare 

 cases do we find a considerable extravasation of blood or even gan- 

 grene near the point where the infection took place. The virus has 



