156 PARASITIC AMOEBA OF MAN. 



old abscesses a mixed infection is generally present 

 and the wall of the cavity is generally smooth or 

 moth-eaten in appearance. In the smaller abscesses 

 the interior is generally almost smooth in appearance, 

 while in the very smallest abscesses no distinct wall 

 can be differentiated. 



The appearance presented by sections of the liver 

 abscess under the microscope varies with the age of 

 the process. In the earliest stage, there is simply a 

 collection of leucocytes and connective-tissue cells, 

 with some congestion of the capillaries in the vicinity, 

 and such sections stained by Mallory's method will 

 sometimes show amoebae, but not as a rule. In those 

 abscesses which have a well-defined wall the centre 

 of the abscess cavity is seen to consist of necrotic 

 epithelium, lymphoid cells, and leucocytes, together 

 with bacteria, and more or less caseous material. 

 Newly formed bile channels are often observed, and 

 examination of the periphery of the small abscesses 

 shows that the process commences in the interlobular 

 areas. The wall of these abscesses is formed by 

 connective tissue considerably infiltrated by leuco- 

 cytes and young connective-tissue cells, and amoebge 

 may sometimes be demonstrated. The liver cells in 

 the immediate vicinity are undergoing necrosis and 

 the bile ducts and capillaries are congested, the bile 

 ducts often being obliterated or encroached upon by 



