Microhic Diseases Individually Considered. 297 



the different organs are congested. When death of 

 the inocuhited animals is delayed they exhibit paraly- 

 sis resembling that observed in the child suffering 

 from this disease. 



The bacilli occur only in the specific lesions; there 

 they secret a poison the absorption of which deter- 

 mines the general symptoms of diphtheria. Cultures 

 freed from microbes by filtration are very toxic ; un- 

 der their influence guinea pigs exhibit a pronounced 

 dyspnoea; rabbits are attacked with progressive 

 paralysis and often with diarrhcea. The dog and the 

 sheep also succumb after showing symptons of paral- 

 ysis. 



The toxic substance of cultures is a diastase pre- 

 senting much analogy with that of tetanus; in the 

 digestive canal it is innocuous. 



Behring appears to have obtained immunity in 

 guinea pigs : 1st, by inoculating them with cultures 

 sterilized at 65° to 70° C; 2d, by injecting them with 

 a mixture of one part of trichloride of iodine and 

 five hundred parts of these same cultures ; 3d, by in- 

 oculating them with the serous or sanguinolent 

 liquid taken from the pleura of guinea pigs dead of 

 diphtheria. 



Avian diphtheria. — Birds are very subject to a dis- 

 ease manifesting itself by the production of false 

 membranes and diphtheritic exudates on -the mucous 

 membranes of the mouth, pharynx, oesophagus, nose, 

 eyes, larynx, trachea, lungs, air cavities, intestines, 

 and upon the skin. This disease is very contagious 

 although much less severe than that of man; like the 

 latter it may occasion rapid mechanical asphyxia, but 

 more frequently it is protracted, presenting remis- 



