§ XIII.] Diphtheria. 173 



tion of the white lining on the mucous membrane of the throat, 

 especially on the tonsils, and it has been proved that by means 

 of this lining the disease can be communicated to a healthyperson. 

 Enquiry was accordingly directed to this substance, and it was 

 found to contain, along with a variety of accidental matters, first 

 of all enormous accumulations of Micrococci, and secondly, small 

 rods in many of the cases which were examined, but not in all of 

 them, as was at first maintained by Klebs. 



Loffler having ascertained the presence of these organisms 

 subjected them to pure culture, and made experimental trial of 

 their efiicacy in the production of disease. 



The Micrococcus in a pure culture forms chains which are 

 very like those of erysipelas. It forces its way from the diphtheritic 

 lining on the mucous membrane into the tissues of a person 

 suffering from the disease, and passes through the lymph-vessels 

 into the most dissimilar internal organs, where it forms nests. 

 It behaved in a similar manner when introduced in the pure 

 state into animals by inoculation, and produced some forms of 

 disease, but did not give rise to the symptoms characteristic of 

 diphtheria. We may therefore ascribe to this Micrococcus the 

 power of producing morbid complications, but we cannot accept 

 it as the specific contagium of diphtheria. 



The rods thrive well on blood-serum, but are difficult of 

 cultivation in other substrata. They are about as long as those 

 of the Bacillus of tubercle and twice as thick, and are otherwise 

 distinguished from this species by marks which cannot be fully 

 described here. They are found collected together in heaps in 

 the lining of the diphtheritic mucous membrane, in the layers 

 beneath the surface. They have not been observed in the in- 

 ternal organs of sick persons. Introduced by inoculation into 

 animals of the kinds usually employed for experiment, they 

 produced symptoms very like those of diphtheria. Loffler there- 

 fore considers that the rods are the contagium of diphtheria in 

 the human subject, though he is careful to draw attention to the 

 objections to this conclusion. 



