4IO Veterinary Medicine. 



Symptoms. The summer sores may appear on any part of the 

 body, but they show a special predilection for parts subjected to 

 friction by the harness, and for the lower portions of the limb 

 from carpus or tarsus downward. They may be individually as 

 small as a millet-seed, or as large as a pea, and in other cases 

 they become aggregated to form patches an inch or even a foot in 

 diameter. The following features are noteworthy : i . The sores 

 as a rule are active only in hot weather and tend to heal over or 

 to remain indolent through winter or during cold weather, the 

 seat of the lesion remaining as a dry, bare, somewhat elevated 

 spot. 2. After the winter the sore breaks out again on the 

 advent of hot weather, and these alterations are noticed year after 

 year. 3. Though comparatively insensible during the winter 

 quiescent stage, the sores become intensely and insupportably 

 itchy when they become active in the following summer. 4. 

 They tend individually to assume a circular outline, and the 

 centre contains a ca.seous, fibroid or calcic material in which in 

 the early stages the minute parasite is to be found. 



In the active stage they show on the surface a soft pulpy layer, 

 easily removed by the nail, exposing reddish brown granulations 

 and minute alveoli with fibrous walls which have been supposed 

 to represent in miniature the marbled lung of lung plague. 

 Sometimes the lesion is superficial so that the entire diseased mass 

 can be scraped off with little or no loss of blood, while in other 

 cases it extends down through the cutis into the subcutaneous 

 tissues. In one case at Ithaca the lateral cartilage was involved 

 so that a considerable portion had to be excised. 



Lesions. The lesions vary according to the season. In the 

 winter the dormant process leaves the affected tissue, in the main 

 fibrous, with- only narrow spaces filled with a caseous or calcic 

 debris. In summer, on the contrary, under the active inflamma- 

 tion, the fibroid material is largely attenuated and replaced by 

 cells, embryonic and fibro-plastic, and the alveolar spaces are en- 

 larged and filled with a greater amount of caseous matter. In 

 proceeding from without inward there is first the wall of organiz- 

 ed fibrous tissue infiltrated by the abundance of cell organisms ; 

 then there is a zone of transition tissue partly fibro-cellular and 

 partly caseated ; finally there is the mass of caseated contents 

 filling the alveolus and in the midst of this is the minute worm 



