Variola : Sheeppox. 353 



form. The typical vesicle is small (5 to 12 mm.), and neither 

 broad and umbilicated like cowpox, nor conical and pointed as in 

 smallpox, but round with a slight flattening on the summit. On 

 the same animal may often be found all the successive stages at 

 once, red points or haemorrhagic spots, vesiculation, pustulation 

 and even desiccation. The earl} 7 changes are seen in the papil- 

 lary layer and rete mucosum, in the form of swelling and conges- 

 tion of the papillae, exudation, active proliferation of the epi- 

 dermic and tissue cells, and migration of leucocytes, (embryonic 

 cells polynuclear) vacuolation of the papule, the spaces being 

 filled with a straw colored exudate, and finally, the replacing of 

 this by pus. If the local inflammation is very acute, the pustule 

 may be resolved into a small abscess. On section of the skin the 

 affected parts are found to be the seat of congestion and gelatinoid 

 exudation, extending into the subcutaneous and intermuscular 

 connective tissue, and even the muscles themselves are blackish 

 and their capillaries engorged. The exudation is especially abun- 

 dant in the dependent parts (head, neck, sternal and abdominal 

 regions, legs). In proportion to the severity of the attack there 

 are congestion, exudation, swelling, and blood extravasation in 

 the lymph glands. 



The nasal mucosa is congested, thickened or even ulcerated 

 with abundant, tenacious, muco-purulent secretion and the nasal 

 chambers narrowed or obstructed, and similar changes may be 

 present in the larynx, trachea and bronchia. Spots of ecchy- 

 mosis and even distinct variolous vesicles are to be expected. 

 The pleurae are often the seat of congestion, petechiae, exudation, 

 and discoloration (red or pale). The lung may show congestion 

 and hepatisation in circumscribed areas, or there may be on the 

 surface of such hepatised portions red or grayish foci, like a lentil, 

 pea or bean, the seat of degeneration or forming minute abscesses. 

 The pericardium and myocardium ma} 7 be involved to a limited 

 extent. 



The buccal and pharyngeal mucosae may be the seats of vesi- 

 cles, or erosions or ulcers the result of their destruction, and the 

 gastro-intestinal mucosa presents ecchymoses, vesicles, abrasions, 

 and open sores in the midst of inflamed catarrhal patches. The 

 mesenteric and other lymph glands are congested, swollen, 

 softened and friable. Congestions and petechiae are found on the 

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