IMMUNITY AGAINST MICEOBES. 433 



but on the third day, should the rat recover, all of them almost 

 are taken into the interior of leucocytes. Amongst the intra- 

 cellular bacilli a great many for a time retain the property of 

 absorbing aniline dyes ; others lose this property, and only 

 stain very slightly. Many of the leucocytes, however, perish, 

 as is proved by the granular appearance of their nuclei. Besides 

 the debris of the nuclei of these phagocytes, more or less de- 

 generated extra-cellular bacilli are sometimes found, which at 

 some time were undoubtedly in the interior of leucocytes. The 

 exudation from the anterior chamber of the eye also contains 

 a more or less large number of macrophages, which, however, 

 do not as a rule destroy many bacilli, but often enclose a large 

 number of leucocytes. 



The following experiment shows that the bacilli are taken 

 into the interior of leucocytes whilst still in the living state. 

 A drop of exudation was removed from the eye of a rat inocu- 

 lated with anthrax after the death of the animal, and at a time 

 when the phagocytes contained a great number of rods ; and 

 after ascertaining that all the leucocytes were really dead a little 

 broth was added to the exudation, and the large drop thus pro- 

 duced placed in the warm chamber. Some hours later it was 

 plain that a certain number of the bacilli were alive in the in- 

 terior of the leucocyte, for they had multiplied and lengthened 

 into filaments. A drop of this exudation introduced under 

 the skin of guinea-pigs produced fatal anthrax in these 

 animals. 



Within the tissues and internal organs of white rats anthrax 

 bacilli are very soon taken into the interior of microphages, or, 

 more frequently, macrophages, e. g. the cells of the splenic 

 pulp, the star-shaped cell of KupflFer, and the mononuclear leu- 

 cocytes found in the capillaries of the liver. As the macro- 

 phages get more and more filled with bacilli the vacuoles 

 increase in number, and the protoplasm at last becomes a mere 

 sac with thin walls, filled with a transparent substance, evi- 

 dently formed by the secretions of the phagocytes and of the 

 parasite. The nucleus, which keeps its characteris tic shape 

 is found in the thickest part of the sac. 



VOL. XXXII, PAET IV. NEW SER. G G 



