36 GKX/iRAL HISTOLOGY. 



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Andral defined it as simple hypersemia. Henle, Stilling, and 

 others refer the dilatation of the vessels, the accumulation of 

 blood in them, and the subsequent exudation, to paralysis of 

 the vessel wall from excitation of the sensory nerves, or reflex 

 through the vaso-motor nerves. This is termed the neuropara- 

 lytic theory. Hoffman, Cullen, and others refer the phenomena 

 to spasmodic contraction of the vessels. This is the neuro- 

 spastic theory. Beale, Simon, Paget, and Virchow ascribe the 

 phenomena to increased nutritive activity of living 1 matter. 

 This may be called the bioplastic theory. 



The formation of pus cells, which are the same as leucocytes, 

 indicates that the blood itself is a factor in inflammation, as 

 well as the vessel wall. Cohnheim maintains the origin of 

 pus corpuscles from blood only and not from fixed tissue bio- 

 plasts, but Strieker claims their origin from both blood and 

 tissues. The latter is most probable, since excess of pabulum 

 may produce proliferation in the bioplasts of both. The mul- 

 tiplication of bioplasts by increased nutrition is more compre- 

 hensible than the vague theory of a mysterious "irritation" 

 strangely propagated through nerves and vessels. 



4. The varieties of exudation accompanying inflammation 

 depend chiefly upon the structure affected. 



(ij Serous exudation, when occurring on free surfaces, is 

 called serous catarrh ; in serous cavities it is inflammatory 

 dropsy; infiltrated in tissues it is inflammatory oedema, and un- 

 der the epidermis it takes the form of vesicles. In albuminu- 

 ria and dysentery the serous exudate is albuminous and coag- 

 ulates spontaneously or by action of reagents, as casts and 

 membranous shreds. 



(2) Mucous exudation is synonymous with mucous catarrh. 

 There is hyperaemia, swelling of the mucous membrane and 

 follicles, excessive production of epithelial cells and mucous 

 elements. If the growth of epithelial bioplasts be excessive, 

 the discharge will be purulent. Catarrhal pneumonia shows 

 increase of the alveolar epithelium of the lobules connected 

 with the bronchial tubes where the catarrh begins. This may 

 become caseous by fatty degeneration and drying. 



In desquamative catarrh of the kidneys there is the charac- 



