EXAMINATION OF THE RESPIRATORY ORGANS. 659 



the corpuscles and granules are mixed with gritty saline parti- 

 cles of an irregular form and size. Crystals of cholesterine are 

 sometimes found in the cretaceous and cheesy varieties of tuber- 

 cle (Fig. 359). If no crystals can be detected, a small quantity 



FIG. 358. 



FIG. 359. 



FIG. 360. 





Section of gray granulations after addition of acetic acid, 

 showing air-vesicles filled with tubercles. 



of alcohol may be added to a portion of the tuberculous mass, 

 and then evaporated. As the evaporation proceeds, the crystals 

 will be fornied. 



Thin sections of calcareous lung present a granular appear- 

 ance, in consequence of the close aggregation of the minute 

 earthy particles. Fragments of the calcareous mass may be 

 broken off, and examined with the low powers of the micro- 

 scope, as in the case of opaque objects generally. A drop of 

 acetic acid added to these fragments causes them to dissolve 

 with effervescence, showing the presence of carbonate. If this 

 solution be treated with excess of ammonia, phosphate of lime 



FIG. 361. 



Fio. 362. 



will be precipitated ; solution of the oxalate of ammonia will 



also detect the presence of lime. 



Irregular, black masses of pigmentary matter, consisting of 

 ceedingly minute molecules, are also frequently found, mixed 



excee 



with tubercle (Fig. 360), giving the tissues a black or bluish 



