PUS. 87 



what smaller, and in thin watery pus, rather larger than the 

 mucus-corpuscles : oval corpuscles, which may be often seen in 

 mucus, and are probably dependent on the viscidity of the 

 secretion, are rarely found in pus. 



In fresh pus the corpuscles are white, opaque, and apparently 

 granular ; when treated with water they become rather larger, 

 lose, in some degree, their granular appearance, and soon 

 give indication of an internal nucleus. With acetic acid they 

 behave exactly in the same manner as mucus-corpuscles ; the 

 capsule becomes transparent and perfectly clear, and the nuclei 

 become visible. The minuteness of the nuclei depends on the 

 number that occur in the pus-corpuscle ; we seldom find more 

 than five, usually two or three. With the aid of a good light 

 we may observe that many of these nuclear-cells possess a cap- 

 sule and nucleolus. Pus-corpuscles dissolve rapidly in free 

 potash, and more slowly in free ammonia. Other reagents 

 produce the same effects as on mucus-corpuscles. 



A very small quantity of dissolved alkali, such, for instance, 

 as occurs in the blood, seems to exert a rapid influence on the 

 form of the pus-corpuscle; for I have seen, in the blood of per- 

 sons who have died from phlebitis, a large quantity of pus- 

 corpuscles, (some isolated, and others swimming in heaps,) which 

 were very pale, larger than usual, and of an irregular and tuber- 

 culated outline. 



The liquor puris, or fluid in which the corpuscles are swim- 

 ming, is transparent, and usually of a pale yellow colour; 

 it contains so large an amount of albumen in solution, that, on 

 the application of heat, it becomes perfectly white, and deposits 

 innumerable flocculi of coagulated albumen. The large amount 

 of albumen associated, moreover, with no trifling quantity of 

 fat, distinguishes the liquid portion of pus from the tough 

 and consistent fluid of mucus, and indicates the affinity be- 

 tween the liquor puris and lymph. The fat is partly com- 

 bined with alkalies, and free fat-vesicles cannot always be de- 

 tected. The largest portion of the fat is apparently contained 

 in the pus-corpuscles ; and, (as I have already observed when 

 speaking of mucus,) the nuclei, if not composed altogether of 

 fat, in all probability contain a very considerable proportion of 

 that constituent ; for, after the addition of acetic acid, I have 

 frequently observed a greater or less number of fat-vesicles in 



