520 GENERAL ANATOMY. 



the first. Among these, pus is the only one which is suffi- 

 ciently well known to be described. 



820. Pus* is an accidental humour resulting from a mor- 

 bid secretion, -which is called suppuration. Pus is composed 

 of microscopic globules, similar to those of the blood, disco- 

 vered by Home, floating in a fluid coagulable by the solution 

 of muriate of ammonia. 



It is of a white or yellowish colour, opake, and of the con- 

 sistence of cream. Its consistence and its colour depend upon 

 ttoe proportion of globules to the fluid part. It is heavier 

 than water. It has a taste slightly saline, constant, and a pe- 

 culiar weak odour, a little variable. 



Pus sinks in water, while mucus floats. By agitation pus 

 becomes diluted, mixes with the water, and whitens it uni- 

 formly; mucus, on the contrary, remains in distinct flocculi. 

 Pus coagulates by heat, acids, and alcohol; alkalies render it 

 viscous, thready, and dissolve it. It is composed, according 

 to Schwilgue, of albumen in a particular state, of extractive 

 matter, of a fatty matter, of soda, of muriate of soda, of phos- 

 phate of lime, and of other salts. It resembles much the se- 

 rum of the blood, from which it appears to differ orjy by the 

 state of the albumen and of the extractive matter. Mucus be- 

 comes diluted in water, dissolves by the. addition of sulphuric 

 acid, while pus does not. A solution of caustic alkali dissolves 

 at the same time pus and mucus, and by the addition of water 

 the pus is precipitated alone. These chemjcal characters, and 

 others of the same Jdnd, are not as certain as the action of wa- 

 ter alone, and especially as microscopic observation. 



* "C. Darwin, Experiments establishing the criterion between irmcagi- 

 nous and purulent matter; Lig-htfield, 1780. Brugrnans, Dissertatio de pyo- 

 genia; Groningse, 1785. E. Home, on the properties of pus; London, 1789. 

 Grasmeyer, Mhandlung von dem eiter, &c.; Getting", 1790. Schwilgue, 

 Mtmoire intdit sur lepus, analyst dans la Nosogr. Philos., vol. ii. G. Pear- 

 son, on expectorated matter; .in Phil. Trans., 1*809. Idem, Observations 

 and experiments on pus; ibid., 1810. Rizetti, De phtJiisi pulmonali specim. 

 chim. med.,- in Mem. de Turin, vol. ii. et iii. --Rossi and Michelotti, Analyse 

 premiere du pus,- ibid., vol. iii. E. Home, On the.oonversion of pus into 

 granulations or new flesh; in Phil. Trans., 1819. 



