188 FAMILY: AM(EBID.E 



amoebae which cannot be obtained so readily from the larger ulcers. 

 After the amoebae have multiplied and caused an extension of the ulcer 

 for some varying period a healing process sets in, the amoebae disappear, 

 and the site of the ulcer is finally represented by a puckered scar of fibrous 

 tissue, while the peritoneal surface opposite it may be considerably 

 thickened. In other situations, however, the process of invasion and 

 ulceration is still continuing, and this affords an explanation of the 

 persistence of infections with E. histoJytica, which are known to last for 



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3 



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O 





''1 



Fig. 94. — Eniamceba histolytica in Tissue of Human Large Intestine ( x 500) 



(Original.) 

 The area is shown in the square at Fig. 93. 



many years, if not a lifetime, unless eradicated by suitable treatment. 

 In their extension through the tissues of the intestinal wall the amoebae 

 not infrequently make their way into blood-vessels, and are carried as 

 emboli to the liver, spleen, brain, or other organ, where they continue to 

 multiply and give rise to the well-known amoebic abscesses. 



In an infected individual, if the amoebae are multiplying rapidly and 

 invading one portion of the large intestine after another in quick succes- 

 sion, the discharge from the ulcers is considerable, and much blood and 

 mucus will appear in the stool, which becomes of the characteristic 



