irS VKSTCITLAR STAGK. 77 



This augmentation in the substance of the epidermoid 

 refiections is probably to be accounted for by the normal 

 secretory functions of the dermis being increased during 

 the formation of the papulae ; in consequence of a 

 larger supply of blood being determined to it than 

 under ordinary circumstances. 



The raj^id growth of cyto-blasts and epidermal cells 

 will not only produce the increased thickness, but will 

 cause much of the effused lymph resulting from the 

 contiiuied inflammation after the nodules are developed 

 to be imbibed by these cells : hence the white aspect 

 of the cuticle ; for this cellular imbibition effects a 

 change in the appearance of the epidermis, analogous 

 to that which takes place on the hands of washer- 

 women after long exposure to the action of water. 



Many of the eruptive vesicles are so small that they 

 will yield no lymph for inoculation, the whole of it being 

 taken up by the epidermal cells ; but when a larger 

 quantity of the fluid exudes from the capillaries, then 

 vesicles more or less distended are produced. In the 

 perfectly formed and matured vesicles of the sheep 

 we do not And the lymph contained in a reticu- 

 lated structure, as in the vaccine vesicle of the human 

 subject ; one puncture, therefore, made in any part of 

 the ovine vesicle is sufficient to evacuate its contents ; 

 but several are needed to effect the same thing in the 

 vaccine vesicle. The modification of organism of the 

 common integument of sheep, depending upon the 

 surface of their bodies being chiefly covered with wool, 

 may probably be a cause of this difference. 



The duration of the vesicular as of the papular 

 stage of variola ovina varies in diflerent cases, and 

 we frequently observe that all the papulae are not 



