248 THE DIPHTHERIA BACILLUS 



4. Infection of mucous membranes. False membranes may be produced 

 by applying traces of culture to the scarified surfaces of the conjunctiva or 

 vulva of the guinea-pig. 



(b) Rabbits. 



The rabbit is far less susceptible to the diphtheria bacillus than the 

 guinea-pig and only succumbs to the inoculation of very virulent cultures. 



1. Sub-cutaneous inoculation. The inoculation of 2 c.c. of a very virulent 

 broth culture leads to the death of the animal in about 5 days. There is 

 an oedema at the site of inoculation : the internal organs are congested and 

 dotted with hremorrhagic points : the inguinal and axillary glands are 

 swollen, the liver jaundiced and friable and shows fatty degeneration : as a rule 

 the lungs are normal : rarely there is some effusion into the pleural cavities. 

 A sub-lethal dose leads to paralysis, affecting chiefly the hind-quarters. 



2. Intra-peritoneal inoculation. The results of intra-peritoneal inoculation 

 are less severe, and death only takes place after some lapse of time. The 

 lesions are similar to those mentioned above. 



3. Intra-venous inoculation. Following the inoculation of 1-2 c.c. of a 

 virulent culture into an ear vein death takes place in from 30-60 hours. At 

 the post-mortem examination an acute nephritis in addition to the ordinary 

 lesions is found : the organisms do not multiply in the blood stream being 

 rapidly taken up by the phagocytes (Metin). 



4. Inoculation on a cutaneous surface. Roux and Yersin obtained excellent 

 examples of false membranes by blistering a small area on the internal surface 

 of the ear and then applying a trace of a culture of the diphtheria bacillus 

 to the exposed dermis. It is essential that the infected surface should 

 not be allowed to dry ; the ear may be enclosed in a small rubber bag. care 

 being taken that the vessels are not compressed at the base. To stop the 

 development of the membrane it is only necessary to uncover the ear. 



5. Intra-tracheal inoculation. A typical condition of croup is produced 

 as in the guinea-pig but more easily. 



6. Inoculation on mucous surfaces. The results are the same as in the 

 guinea-pig. 



(c) Dogs. 



The dog is susceptible to infection with the diphtheria bacillus. 



1. Sub-cutaneous inoculation. Death ensues in 3 or 4 days. Roux and 

 Yersin noted oedema at the site of inoculation, jaundice and finally a pro- 

 gressive paralysis : the fluid of the oedema contained bacilli but the blood 

 was sterile. 



2. Intra-tracheal inoculation. Roux and Yersin produced a swelling of 

 the neck, jaundice, complete paralysis, and death on the fourth day. Post 

 mortem no false membrane was found in the trachea. 



(d) Cats. 



Death follows sub-cutaneous inoculation in 6-13 days. A cat fed on milk 

 from a cow [said to be] suffering from diphtheria with ulcers on the udder 

 also contracted the disease (Klein). 



(e) Cows. 



Klein [claims to have] shown that the cow can contract diphtheria both by 

 spontaneous infection and as a result of experimental inoculation (vide ante). 



Cows inoculated with a young and virulent culture of the diphtheria bacillus 

 died with congestion of the internal organs ; but using agar cultures several days 

 old, Klein was unable to set up a fatal disease. This observer on several occasions 

 noted an eruption on the udder [of cows which had not been experimentally infected] 



