PLASTIC EXUDATIONS. 137 



the transudations is not preceded or accompanied by a true inflam- 

 matory process with complete stasis and with the entire destruc- 

 tion of the blood-cells in the capillaries, as is always the case in 

 the exudations. 



We do not, however, think that it has been satisfactorily proved 

 that the plasticity of the exudation is necessarily dependent upon 

 the presence of these salts, but it is a characteristic of the human 

 mind to catch at the slightest facts for support in the arduous 

 paths of enquiry. Some aid might perhaps be afforded towards 

 the establishment of inductive proof by the results of a series of 

 experiments which I instituted on the blood of horses, comparing 

 the blood of different vessels with the arterial blood. The results of 

 the comparative analyses of eighteen samples of blood from different 

 veins showed that in those capillaries which supply the muscles 

 (organs peculiarly rich in potash- salts and phosphates) the largest 

 number of blood-cells were destroyed ; and that in the venous 

 blood, which flowed from the corresponding parts (from the cephalic, 

 external abdominal, digital, and median veins) there were far 

 fewer blood-cells and a much smaller quantity of the phosphates 

 and potash-salts than in the corresponding arterial blood or in the 

 blood of other veins, which return the blood from other organs. 

 These differences are so considerable, that in the venous blood of 

 the muscles there are on an average from one-fourth to one-third 

 fewer blood- cells than in the arterial blood, whilst in the blood of 

 other veins the difference is either far smaller or there are relatively 

 more cells (that is to say, absolutely less intercellular fluid). 



We have already spoken (in vol. i, p. 361, and vol. ii, p. 310) 

 of the doubt which still exists regarding the influence exerted by 

 the presence of the fibrin on the plasticity of the exudations. 



The present would be a fitting place to consider more atten- 

 tively the more persistent exudations, and to investigate somewhat 

 more circumstantially the chemical metamorphoses which run 

 parallel with the morphological formations, but unfortunately this 

 is a point on which we know little or nothing. As the solidifying 

 parts of the exudation are far less accessible to chemical investiga- 

 tion than the fluid, our attention must of necessity be limited almost 

 exclusively to the latter. I have made some attempts to ascer- 

 tain the differences in the composition of the fluid which occurs 

 in association with the solidified exudation, in so far as they are 

 dependent on the metamorphoses which the original exudation has 

 undergone. We know that these metamorphoses may be of three 

 different kinds ; in the first case, the exudation is gradually resolved, 



