INTEODUCTION. 29 



retrograde process of fatty degeneration, pus-cells seem 

 to be never absorbed. When they have undergone fatty 

 change, and with the Liquor Puris form the so-called 

 Pathological Milk, this may be taken up, just as so much 

 chyle would be, by the lymph-vessels. The blood-capil- 

 laries probably assist, but when neither blood nor lymph- 

 vessels can take up the metamorphosed or unchanged pus, 

 a cold abscess results. Pus is of various kinds : 



Laudable, when it has a creamy, whitish-yellow ap- 

 pearance ; is devoid of smell and rich in corpuscles. This 

 is the form which is familiar to us as occurring in well- 

 matured abscesses. 



Foetid, when it has undergone decomposition, either 

 from a long pent-up condition, or from a depraved state 

 of the parts producing it. 



Sanious, when it is thin and watery, and intermingled 

 with blood in small quantity. 



Ichorous, when thin, watery, almost devoid of cor- 

 puscles, largely made up of cell debris, and often with a 

 marked odour, and an acrid, irritating character. This 

 is produced in parts which are of low organisation, or 

 have been reduced in vitality by long continued diseased 

 action. It occurs in diseases of the feet in long standing 

 fistulous ulcers, where the healing process is at a stand- 

 still. 



Specific, when it contains the virus of some specific 

 disorder, as when it is produced by the mucous mem- 

 branes in cattle plague. Such pus when used for inocu- 

 lation transmits the specific disorder. 



Strumous, when resulting from the breaking down of 

 tubercle. This is white, watery, and has specific cha- 

 racters. 



Pus may be mixed with other fluids as in muco-purulent 

 discharges from mucous membranes. The characters of 

 Inspissated Pus which occurs in chronic abscesses have been 

 already alluded to. 



Caries and Ulceration are processes of molecular dis- 

 integration, which sometimes occur when inflammation 

 cuts off the nutritive supply of a part in a gradual manner. 



