INOCULATION. 115 



the surrounding integument, often to the extent of two 

 or three inches. They cannot be too superficial. In- 

 deed, with })riniary lymph, i. e. lymph procured from 

 the vesicles of a natural case of ovine-pox, we have 

 found that the slightest incision, even if it did not 

 penetrate the dermis, has been followed by an ulcer, 

 varying in sizc^ from that of a shilling to a half-crown. 



That Mr. Ceely's experience agrees with our own is 

 evident fi'om the subjoined extract from one of his 

 letters : — " I find superficial scratches better than 

 ])unctures ; and I place the lymph upon them by 

 means of a portion of moist cuticle recently removed 

 from a vesicle, and secure it with a piece of adhesive 

 plaster : large imnctures are sure to he followed by ex- 

 lejisive or deep and dangerous sloughing." Hurtrel D' Ar- 

 boval has observed similar consequences, and cautions 

 inocidators against inserting the ovine virus beneath 

 the cutis. Our experiments with scratches have not 

 been equally successful with those performed by Mr. 

 Ceely ; notwithstanding that w^e have varied the plan 

 of using the lymph. Adopting this gentleman's recom- 

 mendation, we have fastened portions of the epidermis 

 on the abrasions with adhesive plaster ; at other times 

 we have smeared them over with fresh lymph, while 

 fluid ; and occasionally rubbed in dry lymph, causing 

 it to commingle with the exuded serum. In general, 

 inflammation of an ordinary character has come on, 

 which, as we have elsewhere shew^n (pp. 37-8), has been 

 quickly followed by effusion beneath the cuticle, and 

 the expulsion of the virus from the part. 



For the sake of comparison between the effects pro- 

 duced by scratching and by puncture, we had recourse 

 to the following experiment : — 



