41 8 Journal of Agricultural Research voi. xv, N0.7 



By referring to Table I it will be seen that it was necessary to treat 45 

 cases five times with tincture of iodin in order to get satisfactory results. 

 Thirty of these birds were subsequently treated once with the vaseline- 

 formaldehyde ointment, but are not included in the table. The two cases 

 that required a second treatment with the ointment were very severe and 

 of long standing. All of the cases in this group made a rapid recovery. 



EXPERIMENTAL STUDIES 



Experiments to determine the method of infection in favus were car- 

 ried out as shown below. It should be stated that attempts to infect 

 a fresh, bleeding wound were unsuccessful. 



Hen 138. Scarified small area on comb and wattles. The following day a small 

 quantity of material from an infected bird was instilled beneath the scab. Five weeks 

 later the disease was well under way. Recovery almost complete in six months. 



Hen 610. Infected same as above. Infection very apparent three weeks later. 

 This case grew steadily worse, but finally responded to treatment. 



Hen E146. Infected same as above. Infection apparent 15 days later. Hen de- 

 stroyed and comb used for culture and sectioning. 



Hen 627. Fed large quantities of favus material. No lesions appeared. 



Hen 669. Fed same as above with negative results. 



Hen 10. Fed same as above with negative results. 



Hen E106. Area under left wing scarified, scab removed and favus material in- 

 stilled the following day. No lesions appeared. 



Hen 24. Same as above with negative results. 



Hen E97. Favus material in salt solution was injected into the vein on under side 

 of wing. No lesions appeared. 



Hen 25. Area on comb scarified, the following day scab was removed and small 

 quantity of culture isolated from E146 instilled. Eleven days later infection very 

 apparent. Hen finally destroyed. 



Hen 64. Handled same as above. Six weeks later growth apparent. This hen re- 

 covered about 12 weeks after it had been infected. 



CONCLUSIONS 



These experiments, so far as they go, show that — 

 (i) Favus is primarily a wound-infection disease of the unfeathered 

 parts of the head. 



(2) It occurs usually as an enzootic. 



(3) An ointment composed of vaseline and formaldehyde is an effec- 

 tive remedy. 



(4) Infection by the digestive tract is impossible. 



(5) Intravenous inoculations are incapable of starting infections. 



(6) The organism isolated and studied by us is specific, as shown by the 

 fact that typical cases of the disease were produced in hens inoculated 

 with laboratory cultures. 



