1913] Sweet: Epifhclionw of Ihe Common Fowl 41 



Immwnitij Specific. — The above results were all obtained from 

 a considerable number of cases and show a remarkable agreement. 

 In the cases that were found to be immune after the twelfth day, 

 repeated inoculations, with different strains of virus, were made, 

 but no positive results were obtained. However, in a number 

 of these hyper-immune fowls typical roup was produced by in- 

 oculation with another strain of roup-infected vims. Fally 

 (1908) has observed that an immunity to epithelioma con- 

 tagiosum does not include an immunity to roup, and has argued, 

 therefrom, that each disease is an independent clinical entity. 

 Our results bring us to the same conclusion, and this seems to 

 us one of the strongest reasons for believing the two diseases 

 are due to two distinct causative agents. Seventy-three chickens 

 in all were inoculated. All but ten of these were inoculated with 

 virus which was kept in a test tube, plugged with cotton, from 

 May, 1906, to July, 1910, or with the same strain of virus after 

 one, two, three, or more passages through roup-free fowls. As 

 mentioned above, in some eases the tongues and hard palates 

 were scarified and virulent material rubbed in. In these eases 

 and in about half those in which the comb and wattles alone 

 were inoculated, yellow caseous patches appeared on the mucous 

 membranes of the mouth and throat. However, these patches 

 were well circumscribed in all cases and neither in extent, nor 

 appearance were they typical of roup. Upon examination under 

 the microscope, in the early stages before secondary infection 

 had produced necrotic changes, it was possible to make out 

 changes corresponding exactly to those produced in the epith- 

 elium of the comb. There was an hyperplasia of the epithelial 

 layer of the mucous membrane and cell inclusions of the same 

 nature as those seen in the epithelial growths. At no time, so 

 far as we are aware, has any one seen these inclusions in the 

 lesions produced in the mouth by roup. After a few days these 

 patches become necrotic and were made up of epithelial debris 

 and one was unable to longer make out any definite sturueture. 

 The ten chickens, above referred to, were inoculated with virus 

 freshly received from The College of Hawaii, Honolulu, and the 

 lesions of epithelioma contagiosum differed in no way from those 

 prodviced by our other virus. 



