Diseases of the Respiratory System 169 



affected parts of the mucous membrane as such wounds are 

 likely to be infected and thus become the seat of fresh patches. 

 After thick false membranes are formed it is necessary to re- 

 move them gently before applying the disinfectants. After 

 the drastic disinfectants have been applied to the lesions the 

 throat, mouth and head passages may be disinfected with 

 one of the reagents recommended for catarrh or nasal roup. 

 The potassium permanganate treatment outlined on page 163 

 is the easiest to apply. 



Some workers have used a spray of oil of thyme, oil of 

 eucalyptus or kerosene oil and have reported favorably. 

 Reidenbach ^ tested a large number of antiseptics against 

 fowl diphtheria, among which were 50 essential oils. He 

 found that ajowan oil possesses the strongest antiseptic 

 action. This oil is obtained from the fruit of Ptychotis coptica, 

 an annual plant which resembles caraway and has for its 

 habitat Egypt, Persia and the East Indies. This oil is on 

 the market in this country but is not ordinarily carried by 

 druggists. 



All of these local treatment methods are unsatisfactory in 

 most cases because the germs causing the disease are em- 

 bedded deep down in the tissue underlying the false mem- 

 branes. It is therefore very difficult thoroughly to disinfect 

 the lesions. The tissues injured by strong disinfectants 

 seem especially adapted for the propagation of the surviving 

 pathogenic organism. 



(2) Vaccine and Serum Treatments. — An attack of avian 

 diphtheria confers an immunity, the duration of which de- 

 pends in part at least upon the severity of the attack.^ The 

 fact of this acquired immunity suggests the possibility of 

 establishing an immunity with vaccine and of treating the 

 disease with vaccine or serum. Within the last fifteen years 



' Reidenbach, J., Gefliigel Ztg. (lieipzig), Bd. 26, p. 116, 1910. 

 ' Sigwart, H., loc. cit. 



