BACTERIA IN DIPHTHERIA. 359 



tical value, for diagnostic purposes, of a bacteriological examination 

 of cover-glass specimens and by cultures " of cases in which there is 

 any doubt of the true character of the disease. They say further : 



"The only species of bacteria which we have found constantly in the 

 cases of diphtheria has been the Loffler bacillus. Two other species have 

 been present in many cases, viz., the well-known streptococcus, which grows 

 in much smaller colonies and less rapidly than the Loffler bacillus, and a 

 short, oval, often slightly pointed bacillus, growing in long chains running 

 parallel to each other. There are often marked irregularities in shape and 

 especially in size of this bacillus, even of individuals in the same chain. 

 The colonies of this bacillus are grayish-white, moist, larger than those of 

 the streptococcus, but smaller than those of the Loffler bacillus." 



THIRD. As shown by Ldffler's earlier researches, pure cultures 

 of this bacillus induce characteristic diphtheritic inflammation 

 when inoculated into the mucous membranes of certain lower ani- 

 mals. Roux and Yersin have also shown that local paralysis is 

 likely to occur in inoculated animals, as is the case in diphtheria in 

 man. In speaking of their inoculations into the trachea in rabbits 

 these investigators say : 



"The affection which is thus induced in the rabbit resembles croup in 

 man. The difficulty which the animal experiences in breathing; the noise 

 made by the air in passing through the obstructed trachea the aspect of the 

 trachea, which is congested and covered with false membranes; the oedema- 

 tous swelling of the tissues and glands of the neck, make the resemblance 

 absolutely remarkable." 



Welch and Abbott give the following account of the results of 

 inoculations into the trachea in kittens : 



"A half -grown kitten is inoculated into the trachea with one platinum 

 loop from a pure culture of the Loffler bacillus on glycerin-agar, eleven days 

 old, derived from Case IV. For the inoculation a small median incision was 

 made over the trachea, in which a hole just large enough to admit the plati- 

 num loop was made. The culture was rubbed over the mucosa of the trachea 

 for an extent about three centimetres in length, and in this process sufficient 

 force was used to abrade the mucous membrane. On the day following the 

 inoculation no special alteration in the animal was observed, but on the 

 morning of the second day it was found very weak. In the course of this 

 day it became so weak as to lie completely motionless, apparently uncon- 

 scious, with very feeble, shallow respiration; several times it was thought to 

 be dead, but on careful examination proved still to be breath ing feebly. It 

 was found dead on the morning of the third day. At the autopsy the wound 

 was found gaping and covered with a grayish, adherent, necrotic, distinctly 

 diphtheritic layer. For a considerable distance around the wound the sub- 

 cutaneous tissues were very cedematous, the oedema extending from the 

 lower jaw dow'n over the sternum, and to the sides of the neck, and along 

 the anterior extremities. The lymphatic glands at the angle of the jaw were 

 markedly swollen and reddened. The mucous membrane of the trachea, 

 beginningat the larynx and extending down for six centimetres, wascovered 

 with a tolerably firm, grayish-white, loosely attached pseudo-membrane, in 

 all respects identical with the croupous membranes observed in the same 

 situation in cases of human diphtheria." 



