164 SPECIAL BACTERIOLOGY 



On Potato, which is rendered alkaline, a delicate coating forms. 

 Milk is a favourable medium, and is not coagulated. Owing to the 

 fact that diphtheria epidemics appear sometimes to be spread by the 

 milk supply, Schotellius instituted the following experiments : 1 c.c. 

 of a bouillon culture of the Bacillus diphtheriae was added respectively to 

 20 c.c. bouillon, 20 c.c. fresh milk, and 20 c.c. boiled milk. The 

 fresh milk was obtained direct from the cow's udder, which was 

 previously cleansed. According to the calculation of this author, 1 c.c. 

 of each of the three culture fluids yielded the following number of 

 colonies, as estimated by plate culture methods after six hours' cultivation 

 at ordinary temperature : 



Fresh milk = 21,280-000 Diphtheria colonies. 



Sterilized milk = 2,280-000 



Bouillon = 7,600-000 



After longer incubation at 37 C. : 



Fresh milk = 50,160-000 Diphtheria colonies. 



Sterilized milk = 6,080-000 



Bouillon = 18,240-000 



In cooked and raw eggs the diphtheria bacillus develops in both the 

 white and the yelk very well, also on solid egg albumen, when it some- 

 times exhibits branched forms. 



Vitality. Corrosive sublimate 1 to 1000 kills cultures in thick layers 

 within twenty seconds ; 5 per cent, solution of permanganate of potash, 

 5 per cent, solution of carbolic acid, and 3 per cent, carbolic acid in 30 

 per cent, alcohol, in the same space of time. The pure juice of a lemon 

 kills the bacilli very quickly. They are destroyed when heated at 60 C. 

 for ten minutes. 



In thick layers they resist drying for some months ; when in a dry 

 state they die very quickly. They stand cold well, but in the ice-chest 

 they rapidly lose their power of producing a toxine. According to 

 Loffler the bacilli remain alive in gelatine cultures for 331 days. In a 

 box of wooden bricks with which a child suffering from diphtheria 

 had been playing itself, Abel found Loffler's bacillus six months after. 

 It has also been found in soiled linen, hair, drinking glasses, etc. 

 Diphtheritic membranes dried and kept in the dark are, months later, 

 capable of producing cultures. 



Pathogenesis. Under natural conditions diphtheria does not occur 

 in animals ; the so-called spontaneous chicken and pigeon diphtheria are 

 etiologically different diseases. By inoculation into the trachea in cats 

 and rabbits you get true diphtheritic symptoms general toxaemia and 

 death from absorption of the toxines formed at the seat of disease. 

 Guinea-pigs inoculated subcutaneously with O'l to 0'5 c.c. of a bouillon 

 culture die in from four to five days, showing the following post-mortem 

 appearances : Extensive oedema, hyperaemia, and ecchymosis at seat of 



