164 LYMPHATIC SYSTEM. 



of which it was composed must, I think, have coagulated in- 

 stantly on being secreted from the vessels, otherwise it would 

 have been washed off with the current ; and as the coagulable 

 lymph is not naturally disposed to coagulate so instanta- 

 neously, it is probable that the diseased vessels here possessed 

 the power of producing that change ; and therefore, that as in 

 dropsical habits, where the vessels act weakly, the fluids ex- 

 haled are of a watery tenuity ; so in inflammatory cases, where 

 the vessels act strongly, those secreted fluids, in consequence 

 of that strong action, acquire a more viscid and a more coagu- 

 lable nature (LXXIV). 



And moreover, as it appears that the properties of the lymph 

 exhaled upon surfaces and into cavities differ so widely in differ- 

 ent circumstances, and as we find that pus is often met with in 

 such cavities without ulcerations (see Note LXXII), is it not pro- 

 bable that pus itself is merely that lymph changed in its pro- 

 perties by passing through inflamed vessels? The cavities of the 

 pleura, pericardium, &c., are sometimes observed to contain 

 considerable quantities of pus without the least mark of ulcer- 

 ation, instances of which I have seen. In one patient I found 

 three pints of pure pus in the pericardium, without any ulcer 

 either on that membrane or on the heart. In another, the 

 cavity of the pleura of the right side was distended with a pus 

 that smelled more like whey than a putrid fluid, and the lungs 

 were compressed into a very small compass ; but there was no 

 appearance of ulcer or erosion either on these organs or on 

 the pleura, but only under the pus was a thin crust of coagu- 

 lable lymph. In such cases it is manifest the pus must have 

 been formed from the fluids ; and as the exhalant vessels at 

 one time appear to secrete a mere water, -at another a coagu- 

 lable lymph, and in a third (when a little inflamed) they secrete 

 that lymph so viscid, and change its properties so much as to 

 make it coagulate instantly on being secreted; so in like man- 

 ner they may sometimes, when more inflamed, have the power 

 of converting the lymph into pus ; and, according to the kind 



(LXXIV.) As to the consistency of the liquor sanguinis, and state of 

 the red corpuscles in inflammation, see Note xxm ; detailed experi- 

 ments and historical notices on the subject are given in my paper on 

 Buffy Blood. a 



a Edin. Med. and Surg. Journ. Ixiv, 360 et seq. 



