46 PRilsrcipLEs Of Veterinary siJrGerY 



cocytes appear in acute inflammations, and are sometimes 

 found in pus. They are also present in tissues infected with 

 trichina and animal parasites. Lymphocytes, both small 

 and large, are present in some inflamed tissues, the large 

 predominating. Chronic inflammations, infectious granu- 

 lomata, such as tuberculosis, actinomycosis, etc., attract 

 lymphocytes. Mast-cells .are not always found among the 

 emigrating cells, but appear in some inflammations of the 

 mucous membrane and skin. Myelocytes and nucleated red 

 blood corpuscles most often appear in the neighborhood of 

 bone marrow, from whence they originally come. 



Red blood-corpuscles take part in every acute inflamma- 

 tion, distending the blood vessels and surrounding thern; in 

 some cases they will be found over the entire inflammatory 

 area. Their passage from the blood vessels is purely a pas- 

 sive one, due especially to the increased pressure within the 

 vessel. This is called diapedesis. 



EXUDATES. — Inflammatory exudates vary in quality 

 and quantity according to the tissue concerned, and the na- 

 ture and intensity of the inflammatory agent. Dense tissue 

 allows but little exudation to take place, while vascular 

 structures, cutaneous and serous surfaces readily permit 

 exudation. Some exudates are found in acute inflamma- 

 tions while others are characteristic of chronic. Serous exu- 

 dates occur chiefly in a mild inflammation, but also in certain 

 virulent cases such as anthrax, and are present to some ex- 

 tent in every inflammation. In pleuritis and pericarditis, 

 there may be a large amount of serous exudate, one or two 

 quarts in the pleural or pericardial cavity. The fluid contains 

 little or no fibrin and few or no cells. A fibrinous exudate is 

 characterized by the formation of fibrin ; it does not diflfer 

 materially from a coagulated serous exudate. When the 

 exudate consists of a mixture of fibrin and serum, it is known 

 as a sero-fibrinous exudate. Fibrinous exudates are com- 



