78 SMALL-POX IN SHKKP. 



vesicated at the same time : this chancre comes on 

 a day or two later in some than in others, while 

 several will disappear in the course of the disease 

 without vesicles being produced. Another circumstance 

 worthy of note is, the non-existence of any areola in 

 the early stages of vesication ; indeed, it is only when 

 the vesicles are fiillv matured, and their contents are 

 becoming purulent, that areolae are seen ; and even 

 then they are neither deep in colour, nor extensive. 



The ovine vesicle is flat on the surface ; and in this 

 particular it forms a contrast both with the vaccine 

 vesicle of the cow and with the variolous of man : in 

 the former disease it is found to rise in an acumi- 

 nated shape from the papula, and in the latter to be 

 umbilicated in the middle. The central depression 

 occasionally exists in the perfectly developed vesicle of 

 the sheep-pox, when a crust is formed on its middle ; but 

 if the cuticle dries and produces a scab of the full size 

 of the vesicles, then umbihcation is not present. 



In the progress to maturation, the contents of the 

 vesicles undergo similar changes to those that are pro- 

 duced by ordinary causes : thus, at first they are dis- 

 tended by a clear and hmpid fluid ; this soon becomes 

 opaline, or m'llkij ; then turhid, less serous, and straw- 

 coloured ; and ultimately, by drying, hardens into a crust, 

 and is cast off with the epidermis. This description 

 of the changeable appearance of the vesicles agrees with 

 the observations of Mr. Ceely, who, in a letter which 

 we have received from him, gives a similar account 

 of their progress : he also adds, that when he first saw 

 the ovine crusts, he felt doubtful of the correctness of 

 the term pustule, as applied to the eruption ; and has 

 satisfied himself that it is not essentially a pustular 



