330 A MANUAL OF BACTERIOLOGY 



Schick test, while true cases will give a positive Schick 

 test. 



Guinea-pigs are the animals generally employed for 

 experimental work on diphtheroid organisms. In order 

 to compare the effects and virulence of various bacilli it 

 is customary to make the inoculation with a measured 

 volume of a forty-eight hours' broth culture. From 0-1 

 c.c. to 2 c.c. of such a culture, according to the virulence, 

 inoculated subcutaneously, is usually required to kill a 

 250-grm. guinea-pig within three days. At the seat of 

 inoculation hsemorrhagic oedema forms, haemorrhages 

 occur in the serous membranes, and especially in the 

 adrenals, while the renal epithelium and the liver-cells 

 undergo cloudy degeneration. 



Inoculated into the trachea of the guinea-pig, rabbit, 

 and chicken, pseudo -membranes form, and the same 

 occurs with the superficially injured conjunctiva and 

 vagina. It is stated by some that the diphtheria bacillus 

 does not develop on a normal mucous membrane this 

 must first be injured, and the staphylococcus and strep- 

 tococcus, so often associated with the diphtheria bacillus 

 in the human subject, may play a part in preparing the 

 way for infection by damaging the cells and tissues. 

 Rabbits usually live somewhat longer than the guinea- 

 pig after inoculation, and paralysis frequently develops 

 if life is prolonged, analagous to the post -diphtheritic 

 paralysis of man. 



The question of the occurrence of the Klebs-Loifler 

 bacillus in the lower animals is of considerable importance 

 with regard to the spread of the disease and the convey- 

 ance of infection. The so-called diphtheritic affections of 

 pigeons, poultry, and calves (referred to more in detail 

 at p. 355) are as a rule diseases quite distinct from human 

 diphtheria, and are not communicable to man. A 

 number of observers have asserted that cats may suffer 



