BACILLUS DIPHTHERIA. 238 



repeated supposed discoveries of the diphtheritic bacteria 

 rested on errors. Of late Loeffler has attempted to clear J 

 up the etiology of diphtheria by the employment of 

 better methods, and by bearing carefully in mind the 

 sources of error. He found in sections of diphtheritic 

 membranes that, in addition to what were evidently 

 accessory organisms, two kinds were present which were 

 of special interest ; on the one hand, cocci which were Streptococci. 

 arranged in the form of chains, and chiefly occurred in 

 the diphtheritic throats in cases of scarlet fever. These 

 had their starting point usually in a loss of substance of 

 the diseased mucous membrane, and extended from that 

 point into the tissue in the form of wedge-like or tongue- 

 like masses, leaving necrosis of the tissue behind them ; 

 they penetrate into the lymphatic vessels, and at times 

 spread through the whole body. That these chains of 

 cocci play a secondary role in diphtheria is probable 

 from the fact that in other diseases accompanied by 

 lesions of mucous membranes we can observe a similar 

 growth of streptococci ; and further, they were not so 

 much characteristic of typical cases of diphtheria, with 

 a definite membrane in the throat and with spread of 

 the process to the air passages, as of cases of scarlet 

 fever, in which the process remains limited to the throat. 

 As to the characters of these cocci on cultivation, and 

 in experiments on animals, see page 194. 



The other bacteria found by Loeffler in the majority Loeffler'* 

 of the cases of typical diphtheria are rods with peculiar 

 morphological and biological characteristics; they are 

 probably identical with the form of bacillus which was 

 also found by Klebs in diphtheria, and was looked on 

 by him as the infective agent of the disease, although he 

 did not succeed in obtaining pure cultivations of the 

 organisms. Loeffler found these bacilli, which stain 

 markedly with methylene blue, in the false membranes 

 at a deeper level than the masses of other bacteria 

 which covered the surface, namely, at the inner margin 

 of the layer of exudation ; they also occupied the oldest 

 portion of the membrane, and penetrated deeper than membrane. 

 all the other bacteria. Cultivations could not be made 



