TEXT-BOOK OF BACTERIOLOGY. 135 



inoculate an animal susceptible to full-strength anthrax with at- 

 tenuated anthrax bacilli. These attenuated bacilli have lost their 

 invulnerability, have been robbed of their dangerous character, and 

 this time they become the prey of the phagocytes. The phagocytic 

 theory cannot explain why, in one case, the bacteria always con- 

 quer, in another always the cells; why the virulent micro-organ- 

 isms alone are able to conquer the opposition which the tissue ele- 

 ments offer to them. It contents itself with stating the fact, and 

 does not attempt an explanation. Serious objections have been 

 raised by very high authorities against MetschnikofFs views. 

 Fliigge, Baumgarten, and Weigert, in particular, have opposed 

 them, stating that a reception of bacteria by the cells of the body 

 only takes place when the former have been already killed, or at 

 least been deprived of much of their vital energy by other influ- 

 ences. The phagocytes, they maintained, did not form an active 

 and dangerous weapon of defence for the organism, did not stand 

 in the foremost rows in the battle against the invading parasite, 

 but were the open graves behind the line of battle, destined to re- 

 ceive the fallen enemies or any other lifeless bodies or substances. 

 Nothing, they said, compelled us to believe that these cells pos- 

 sessed a peculiar devouring and digesting power: they were, on the 

 contrary, nothing but buriers of the dead, removers of decaying 

 matter. They maintained, further, that whenever healthy, vigorous 

 bacteria entered the cells these latter always fell a sacrifice to 

 them and were irretrievably lost. 



In fact, the opinion that bacteria are destroyed by influences 

 lying outside the cells has received a strong confirmation in the 

 recent observations of the germ-killing power of blood-serum sepa- 

 rated from cells. 



It cannot be denied that Metschnikofr's theory agrees ill with 

 the revelations of physical science in general, which exhibits life of 

 all kinds as depending on processes, physical and chemical, which 

 obey the simplest laws. It would, as already said, be more com- 

 prehensible if we could see the cells in a less immediate strife with 

 the bacteria, and if both were represented to us as the special ex- 

 citers of definite processes, chiefly of a chemical nature, which^then 

 in their turn began to act upon each other. Yet the phagocytic 

 theory, perhaps on account of its palpable character, has, neverthe- 

 less, gained numerous adherents, who hold fast to it and defend it 

 against all attacks, so that it cannot be left out of account in dis- 

 cussing the matters with which we are dealing. 



Whether the obstacles which the organism opposes to the in- 

 vasion of bacteria be of a chemical or cellular nature is not the 



