BACILLUS DIPHTHERIA. 397 



If a very minute portion of either a solid or fluid 

 pure culture of this organism be introduced into the 

 subcutaneous tissues of a guinea-pig or kitten, death of 

 the animal ensues in from twenty-four hours to five 

 days. The usual changes are an extensive local oedema, 

 with more or less hypersemia and ecchymoses at the 

 site of inoculation ; swollen and reddened lymphatic 

 glands ; increased serous fluid in the peritoneum, pleura, 

 and pericardium ; enlarged and hemorrhagic adrenal 

 bodies ; occasionally slightly swollen spleen ; and some- 

 times fatty degeneration in the liver, kidney, and myo- 

 cardium. In guinea-pigs, especially, the liver often 

 shows numerous macroscopic dots and lines on the sur- 

 face and penetrating the substance of the organ. They 

 vary in size from a pin-point to a pin-head, and may be 

 even larger. They are white and do not project above 

 the surface of the capsule. ^ 



The bacilli are always to be found at the site of inoc- 

 ulation, most abundant in the grayish-white, fibrino- 

 purulent exudate. They become fewer at a distance 

 from this, so that the more remote parts of the oedema- 

 tous tissues do not contain them. They are found not 

 only free, but contained in large number in leucocytes, 

 some of which have fragmented nuclei, or have lost 

 their nuclei. The bacilli within leucocytes, as well as 

 some outside, frequently stain very faintly and irregu- 

 larly, and may appear disintegrated and dead. 



Culture-tubes inoculated from the blood, spleen, liver, 

 kidneys, adrenal bodies, distant lymphatic glands, and 

 serous transudates, generally yield negative results ; and 

 negative results are also obtained when these organs are 

 examined microscopically for the bacilli. 



Microscopic examination of the tissues at the site of 



