EXUDATION'S. 185 



though the fact shows that stasis of the blood is not necessary to 

 exudation, as some have maintained. 



2. It follows, therefore, that exudations differ from transudations 

 in their constituents, since the latter are not organizable, and there- 

 fore cannot become the medium of the reparative process, nor be 

 converted into adventitious growths in cases of inflammation. In 

 exudations a considerable amount of fibrine is almost always pre- 

 sent; 1 an element always wanting, we believe, in mere transudations 

 (p. 183). There is also far more albumen in exudations, and the 

 phosphates and potassium compounds are more abundant. Blood- 

 corpuscles, more or less altered, are also often found in fresh exuda- 

 tions ; but they are not an essential constituent, and depend upon a 

 rupture of the minute vessels of the part. Sometimes, also, the 

 exuded fluid, in case of inflammation, is stained by the haematine 

 which has been dissolved out of the blood- corpuscles stagnant in 

 the inflamed part. Exudations, indeed, approximate more nearly 

 to the blood-plasma, and transudations to the blood-serum merely. 

 But the latter are never precisely identical with the serum ; and 

 exudations abound far more in water and in the phosphates than 

 does the liquor sanguinis, while they contain less fibrine. 



Thus it appears that no histological elements exist in pure exu- 

 dations when first separated from the blood, though the former are 

 soon developed in them, unless the exudation is promptly reab- 

 sorbed, as will appear. 



Origin. Exudations are poured directly from the bloodvessels 

 of the part ; and as they normally contain no blood-corpuscles, no 

 rupture of the vessels is required for their effusion, any more than 

 in the case of transudations. The exudation in an incised wound 

 is entirely free from blood-corpuscles, and occurs after all hemor- 

 rhage ceases. Exudation is not, therefore, a modification of secre- 

 tion, no cell (epithelial or otherwise) nor other special structure 

 being required for their production. In inflammatory exudations, 

 blood -corpuscles are frequently also found, since rupture of the ves- 

 sels, and consequent hemorrhage, is a very common concomitant of 

 inflammation. It is in accordance with a vital law of the organism 

 that where new material for repair is required, or wherever an inflam- 

 mation occurs, an exudation is poured out from the vessels of the part. 



1 Lehmann states, however, that plastic exudations sometimes occur without 

 fibrine (vol. ii. p. 290). Non-plastic exudations also contain it. 



