PUS. 89 



irregular fragments of tubercle appear to the eye to be of a 

 caseous nature ; but, after being moistened with water,, sub- 

 mitted to pressure between two pieces of flat glass, and placed 

 under the microscope, they seem to be composed of an amor- 

 phous, finely granular, opaque, yellow matter, in which there 

 are a varying number of fat-vesicles and some minute ramifying 

 tubuli or fibrils, as in fig. 18. We sometimes meet with pecu- 

 liar forms in tubercle, which, doubtless, belong to the tissue or 

 vessels of the lung; they have likewise been observed by Gruby, 

 and I have represented several of them in fig. 19. 



Gruby has observed peculiar corpuscles in tubercle which I 

 have hitherto sought for in vaiii, both in tubercular lungs and 

 in expectoration, and which he regards as characteristic of that 

 morbid deposit. He describes them as lenticular, round, or 

 oval, whitish-yellow corpuscles, with concentric rings, their 

 lamellse being arranged in the same manner as those of an onion, 

 and their size being from two to ten times as large as a pus- 

 corpuscle; they are frequently jagged at the edges, dissolve 

 easily in caustic potash, and become distended in nitric acid 

 and a solution of nitrate of silver. 



It appears from the preceding observations that pus consists 

 of two distinct portions ; namely, of a fluid, the liquor puris ; 

 and of corpuscles swimming in this fluid and insoluble in it. 

 The corpuscles are surrounded by a capsule, which becomes 

 tumid in water, is soluble in free potash and is reduced by 

 ammonia to a thick viscid jelly, dissolves on prolonged gentle 

 digestion, and is doubtless composed of mucin. Of the nature 

 of the contents of the corpuscles lying between the nucleus 

 and the capsule we know nothing ; the nucleus probably con- 

 sists of albuminous matter and fat. The liquor puris con- 

 tains albumen, fat, pyin or dissolved mucin, extractive matter, 

 and salts. For the quantitative analysis of these substances I 

 adopted the same method as in the analysis of mucus. (See 

 page 75.) 



Giiterbock's quantitative analysis of pus was made in the 

 following manner : Pus was boiled with anhydrous alcohol, and 

 filtered while still hot ; on cooling, the fat separated. The clear 

 alcoholic solution was evaporated, and the residue treated with 

 water, which dissolved the extractive matter and some free acid, 



