TEXT-BOOK OF BACTERIOLOGY. 131 



for the bacteria to live in them. Considering this with the previ- 

 ously-mentioned observations of the same investigator, we gain a 

 valuable hint for the explanation of these things. Although the 

 blood of susceptible animals may oppose to the micro-organisms a 

 resistance equal in quality, but different in amount, an alkalescence 

 small, perhaps, but yet injurious in its action, we may well conceive 

 that virulent anthrax bacilli, with their decidedly acid excretions, 

 are able to conquer this difflcultj'. They lessen the alkaline char- 

 acter of the juices of the body, and acquire the capacity of thriving 

 in it — they take an infectious character. 



Attenuated bacilli, on the other hand, are not able to make their 

 way in like manner. If they form alkali instead of acid, they will 

 even add to the difficulties which they found at first, and will be 

 wrecked on this first rock, even though they may find all the other 

 conditions for their parasitic existence. 



In this way the greater or less mass of acid production would 

 explain all the different degrees of virulence, and incline us to re- 

 gard them all as purelj' chemical phenomena. We must, it is true, 

 be on our guard against thinking the matter altogether so simple. 

 The composition of blood is not always uniform, and we cannot 

 credit it with a definite chemical formula. It depends on the state 

 of the tissue-cells, and is only the special expression for the condi- 

 tion of these cells. Therefore we are only justified to a certain ex- 

 tent in regarding the influence of the acid anthrax bacilli on the 

 alkaline blood as if the one neutralized the other, as one chemical 

 neutralizes another in a test-tube. We must rather suppose that 

 the cells of the body also come into play, since they are subject to 

 the influence of the bacterial excretion, and in consequence of this 

 influence they modify their own excretions, which now first become 

 advantageous to the micro-organisms. That in realitj- these rela- 

 tions are more intricate than we might suppose at the first glance 

 has been vfery clearly shown by the most recent investigations. It 

 would seem that the powers of resistance offered by the bodies of 

 animals against bacteria are by no means of a universal character, 

 but possess a clearly special — one might almost say specific — char- 

 acter. 



If we introduce bacteria, of any species whatever, into the blood- 

 vessels of an animal, we notice that they disappear thence in a 

 short time. Where do they remain then ? It was at first supposed 

 that they must leave the body along with its secretions, and that 

 thej' would be found in the urine, the bile, etc. Yet careful investi- 

 gations, among which I may particularly note those of Wyssoko- 

 witsch, have shown that the filtering mem-branes in their uninjured 



