210 TECHNICAL BULLETIN U 



were modifications of the metliod of Panisset and Verge (8). Approximately 

 1 sq. c-:.i. t)f c'oiiil) area was curetted or scraped until Ipnpli was drawn. 

 Care was exercised not to produce a bleeding surface. Virus suspensions, 

 unattenuated and attenuated by moist heat at 55° C. for one hour, were 

 rubbed into the areas. Well formed epitheliomata always developed after 

 the usual incubation period of from four to seven days, but in at least .50 per 

 cent of all cases the lesions spread to contiguous surfaces of the comb, not 

 remaining localized. The virus content of the suspensions was decreased 

 until 200 milligrams of virus in 50 cc. of physiological saline solution were 

 used. The results were about the same. The suspensions were then injected 

 intracutaneously in 0.1 cc. doses, into a barb of the comb. This method of 

 administering the vaccine greatly decreased the number of cases that pre- 

 sented lesions on the comb after the vaccination other than at the point of 

 inoculation. 



After the local lesions had fully cleared up in the l)irds used in these experi- 

 ments, the combs were lightly scarified and unmodified virus rubbed into the 

 areas to test the degree of immunity production. In all cases where local 

 lesions had developed following vaccination, the immunity was complete or 

 nearly so. 



Experimental Skin Vaccination. 



At the same time tliat tlie above experiments were in progress, various 

 efiforts to induce a local or cutaneous imnumity by feather follicle vaccination 

 were being made. Young and healthy White Leghorn cockerels, four to eight 

 months old, were used in tiie experiments. 



In the following experiments the place selected for vaccination was on the 

 outside of the right leg just above the tibio-femoral joint. An area of ap- 

 proximately 1 square inch was denuded of feathers, cleansed with sterile 

 physiological saline solution, dried with sterile cotton, and the vaccine ap- 

 plied by rubbing into the follicles with a cotton swab attached to a wooden 

 applicator. The left leg was similarly treated for control purposes, saline 

 solution being used instead of vaccine. The experiments described below 

 differ only in the vaccine used and the method of preparing tJie feather fol- 

 licle area prior to the administration of the vaccine. 



Experiment 1. 



Twelve birds were used. The vaccine M^as an unattenuated suspension of 

 0.5 grams of pox virus in 50 cc. of physiological saline solution. The bared 

 feather follicles and interfollicular spaces were lightly scarified and the vac- 

 cine applied by rubbing into the area with a cotton swab attached to a 

 wooden applicator. Five days later a definite swelling of the follicles had 

 developed and scab formation over the orifices of the follicles was in progress. 

 On the tenth day after vaccination, the scab formation was fully developed. 

 The infection became generalized, pox lesions aj)pearing on the comb and 

 eyelids, in four of the birds. A systemic reaction, as evidenced by droopi- 

 ness, lethargy, etc., also occurred in these four birds. 



While scab formation was taking place, a local pyogenic inflammation 

 develo])ed, which was undoul)tcdly due to the Staphylococcus aureus and 

 Pseudomonas aermjinotia content of the fresh virus (2) used in the vaccine. 

 It was evident that scarification of tlic skin and feather follicles induced this 

 local inflammation. Scarification was, therefore, contra-indicated. 



Tiie fejither follicle scabs were removed, dried, pulverized in a mortar, 

 susjtended in saline solution and ap))lied to tiie scarified comli areas of normal 



