South African Horse Sickness, etc. 517 



cated in some cases, more commonly the exudation appears to a 

 slight extent in all three situations, and it is only the predomi- 

 nance of the symptoms in one particular part that assigns the 

 attack to one type rather than another. All are very fatal, but 

 the lung sickness is preeminently so, very few such surviving. 



Lesions. There is usually a mass of white froth around the 

 mouth and nostrils. The serous exudate coagulates readily in 

 the presence of minute traces of blood, and forms a solid mass of 

 clot when heated. A yellow gelatinoid exudate is found in 

 streaks or patches, subcutaneously and between the muscles, but 

 especially along the jugular furrow. In the head sickness the 

 whole subcutaneous and intermuscular tissue in the head and 

 neck are infiltrated, and the straw-colored liquid escapes abun- 

 dantly when the part is scarified. The same is true of the tongue, 

 which is stained throughout with blood that has gravitated intoit. 



The pleurae contain an abundant exudate more or less deeply 

 stained with blood. The same is true of the pericardium. In 

 the latter Ediugton has found 140 fluid ounces. On the surface 

 of the lungs and pericardium are extensive yellowish exudates. 

 They are covered with petechise mostly small or punctiform. If 

 the horse has stood at rest throughout the illness the lungs seem 

 pale, yellowish, yet swollen and indisposed to collapse. The in- 

 terlobular tissue especially is infiltrated with serum so that toward 

 the free margin the lobules may be separated by intervals of half 

 an inch in breadth as in lung plague of cattle. In horses that 

 have been worked during the illness the whole organ is congested 

 and firm, resembling the condition of croupous pneumonia. The 

 trachea and bronchia show dark congestion of the mucosae and a 

 mixture of froth and serous exudate. The large blood vessels 

 contain diffluent blood clots of an intensely dark color. In the 

 vascular furrows of the heart and along the large vessels are yel- 

 low exudates or blood extravasations. The muscular tissue of 

 the heart appears normal or rather pale, and under the micro- 

 scope the striae are found to be obscured by cloudy swelling, and 

 minute blood extravasations and haematin are met with. The 

 endocardium is cloudy, with blood extravasations, and exception- 

 ally ante-mortem clots are found. The spleen is usually swollen, 

 very dark, blood gorged and covered with petechiae. On section 

 there are found extensive extravasations, with masses of blood 

 pigment and crystals. The kidneys are enlarged, the capsule 



