498 PNEUMONIA. 



stage of grey hepatization is the difference in colour, which 

 varies from a reddish -brown to a grey or yelloAvish-white, and 

 appears to be owing chiefly to two conditions, that of pressure 

 exercised upon the minute bloodvessels by the adventitious 

 products of the inflammatory action, and the degenerative 

 fatty changes Avhich have occurred, and are occurring, in the 

 cell-elements of the product. 



Besides this alteration of colour from brown to grey, we have 

 also the continued existence of the impervious character, im- 

 possibility of inflation, and increased density and friability of 

 the previous stage of red hepatization : it wants resilience, and 

 sinks in water. On incising a portion of lung-tissue in this 

 condition we find appearances and characters varying from 

 each other in different individuals, as they vary in all from the 

 former stage of red consolidation. The granular character, 

 either in a torn or cut surface, is less distinguishable in the 

 grey than in the red hepatization. In the horse, in some cases, 

 the previous well-distinguished granular condition of the red 

 hepatization may still be perfectly distinguished ; in other 

 cases matters are very much similar to what we encounter in 

 the lung-tissue of bovines undergoing this modification of 

 pneumonic inflammation, Avhere the grey material is firmer and 

 of the planiform character, which it maintains throughout the 

 course of the disease. 



Although these several conditions of engorgement, red, and 

 grey hejmtizatioTi , are tolerably uniform and regular, in per- 

 fected cases of pneumonia, in the sequence with which they 

 succeed each other, we have ever to remember that even 

 this may be interrupted ; that cases, for example, may show 

 themselves where diftuse suppuration is established without 

 the intervention of red hepatization, and that each is in very 

 many instances shaded oft' and imperceptibly passes into the 

 other, while it may be that some two of these otherwise 

 distinct states may coexist in the same lung-structure. Also 

 that there are many cases, chiefly those of secondary pneu- 

 monia, occurring in connection with, or as a sequel of, some 

 other diseased action where these states of consolidation are 

 much less perfectly carried out, and where the various steps 

 and changes of the process undergo much modification. 



Besides these common and usually encountered pathological 



