284 MANUAL OF BACTERIOLOGY. 



The diphtheria bacillus is pathogenic to animals. When 

 it is injected into them it produces a toxemia. In the 

 guinea-pig, which is especially susceptible, local inflamma- 

 tion results, and death occurs usually in two or three days. 

 The bacilli are found to be confined to the vicinity of the 

 wound, and not usually to be disseminated throughout the 

 whole body. The death of the animal, therefore, is due to 

 the poisons elaborated by the diphtheria bacilli either 

 poisons introduced at the original injection, or substances 

 produced by the bacilli which may have multiplied in the 

 animal's body. The internal viscera, especially the liver, 

 often exhibit small areas consisting of necrotic cells; a 

 transudation of serum takes place in the great serous cavi- 

 ties, and the lymph-nodes are swollen. A genuine diph- 

 theritic membrane may be produced on the trachea of a 

 young kitten by rubbing into it a part of a culture of the 

 diphtheria bacillus. 



As is well known, the pseudo-membranous affection pro- 

 duced by the diphtheria bacillus in man is generally seen in 

 the larynx and pharynx. Membranous rhinitis is also 

 caused by the diphtheria bacillus. On the other hand, 

 pseudo-membranous affections of the larynx and pharynx 

 may be produced by streptococci. Pseudo-membranes 

 occurring in the throat during scarlet fever and measles 

 may be due to the diphtheria bacillus, but are more 

 often caused by streptococci. The affection known as mem- 

 branous croup is usually diphtheria of the larynx, produced 

 by the diphtheria bacillus. The diphtheria bacillus is a rare 

 cause of puerperal fever. Although the uninjured skin is 

 not attacked by the diphtheria bacillus, it may be present in 

 pseudo-membranes on wounded surfaces, usually in con- 

 nection with diphtheria in the throat. Most pseudo-mem- 

 branes formed upon wounds of the skin are produced by 

 other bacteria than the diphtheria bacillus, as is also the case 



