84 THE SECRETIONS: 



pus. When tubercles form in the lungs, they produce, like 

 any other foreign body, a degree of irritation in the surrounding 

 tissue, and an increased secretion of mucus is the result. Gruby's 

 observation that the mucus discharged during irritation of the 

 mucous membrane, dependent on the deposition of tubercle, 

 does not differ from the mucus produced during catarrhal 

 affections, is confirmed by Hetterschig 1 and other observers; 

 the secretion of mucus at the commencement of a catarrh is, 

 however, more abundant than that which is produced by the 

 irritation of existing tubercles. 



The quantity of expectoration increases with the more ex- 

 tended deposition of tubercle, until softening commences ; the 

 tubercular matter is then expectorated, and, in consequence of 

 the inflammation that occurs, pus is secreted by the walls of the 

 cavity thus produced, and in this manner gets mixed with the 

 sputa. 



The purulent expectoration of persons with tubercular phthisis 

 is easily distinguished by the experienced practitioner from 

 healthy sputa, 2 and with tolerable certainty from diseased mucus, 

 nor can there be any doubt regarding its nature while tuber- 

 cular matter is being discharged from a vomica, but the tran- 

 sition from diseased into healthy purulent mucus is so slight and 

 imperceptible, that it is hardly possible to detect the first traces 

 of pus that are mingled with the mucus; for although, as I 

 shall presently show, their general physical and chemical rela- 

 tions are perfectly sufficient to distinguish pure pus from pure 

 mucus, we have no means of determining with certainty the 

 presence of a little pus in mucus, or the presence of a little 

 mucus in pus. 



Purulent mucus from the lungs contains much less mucin 

 than normal or diseased mucus, 3 and consequently the mucous 

 clots have not the toughness, lubricity, and consistence ob- 

 served in mucus, unmixed with pus : in fact they have a de- 

 cided tendency to dissolve. Purulent mucus sinks more 

 quickly in water than the normal secretion, partly in conse- 



1 De Inflammatione ejusque exitu diverse. Trajecti a. R. 1841, p. 176. 



a [Dr. Wright's papers on Expectoration (recently published in the Medical Times) 

 may be consulted with advantage.] 



3 [This is perfectly consistent with the observation of Eichholtz, that the pyin (or 

 mucin) varies inversely with the pus-corpuscles.] 



