398 ACTINOMYGETES. 



2. Mixed infection with streptococci and diphtheria 

 bacilli is more dangerous for the animal than pure diph- 

 theria infection. 



Nevertheless the diphtheria bacillus alone may undoubt- 

 edly produce all the clinical symptoms of sepsis (Gener- 

 sich). 



(d) In animals : Certain spontaneous disease produced 

 by Loffler's bacillus has never been observed in any ani- 

 mal. The susceptible guinea-pig is immune to the diph- 

 theria bacillus introduced by feeding, by inhalation, or 

 by swabbing. Spontaneous disease (diphtheric broncho- 

 pneumonia) is said to occur in cats (E. Klein, C. B. yiii, 

 7). Klein claims also to have observed spontaneous diph- 

 theria in milk cows, in which, moreover, the diphtheria 

 bacilli escaped in the milk. 



The spontaneous diphtherias of hens, pigeons, ^ and 

 calves always (?) have other causes. (Compare LofHer, 

 Mitt. G. A. ii; Ritter, H. K, 1896, 839). 



Still, certain of the causes of "animal diphtheria" 

 appear to be transferred to man. Consult the well-known 

 observation of Gerhard (II. Kong. f. innere Med.), and 

 also Galli-Valerio (C. B. xxii, 500: extensive critical 

 review of literature). 



Experimental Observations Regarding Pathogenic 

 Effects. — (a) Upon animals : The virulence of freshly iso- 

 lated cultures varies greatly; in general, severe cases fur- 

 nish virulent cultures and mild ones cultures with slight 

 virulence; still, there are exceptions. Experimental and 

 accidental (cultural) attenuation is often observed. Roux 

 and Yersin assert that there occurs a regular, striking re- 

 duction of virulence in the last few diphtheria bacilli 

 demonstrable during convalescence. It was not found so 

 b}' Escherich, and still other writers cultivated virulent 

 bacilli from convalescents long after the clinical sj'mptoms 

 disappeared. A good standard for the virulence of a cul- 



' Gallez claims to have positively demonstrated in Belgium that, 

 besides the " fowl diphtheria," which has nothing to do with human 

 diphtheria, there is also a " fowl glanders, ' ' which is caused by attenu- 

 ated Loffler's bacilli (H. E., 1896, VI, 472). 



