EXPERIMENTAL INOCULATION 



607 



and are largely constituted by necrosed and liquefied tissue with 



admixture of blood in varying amount. Microscopic examination 



shows chiefly necrosed and granular cells and debris resulting 



from their disintegration, whereas ordinary pus corpuscles are 



-rant y or may be practically absent. In such abscesses associated 



with dysentery the amoebae are usually to be found, and not 



infrequently are the only organisms present, no cultures of 



bacteria being obtainable by the ordinary methods (Fig. 170). 



They are most numerous at the spreading margin, and this 



probably explains a fact 



I "tin ted out by Manson, 



that examination of the 



contents first removed may 



give a negative result, 



while they may be detected 



in the discharge a day or 



two later. The action here 



on the tissues is of an 



analogous nature, namely, 



a necrosis with softening 



and partial liquefaction, 



attended by little or no 



suppurative change. The 



anni'baj have also been 



found in the sputum when 



a liver abscess has ruin FIG. 170. Section of wall of liver absce-ss, 



showing an amoeba of spherical form 

 with vacuolated protoplasm. From a 

 case published by Major D. G. Marshall. 

 xlOOO. 



into 



thp 



not very infrequently 

 happens. Kartulis records 

 two cases of brain abscess 



occurring secondarily to dysentery in which numerous amoeba; 

 were present. 



Experimental Inoculation. The anatomical changes in 

 dysentery, as above described, give strong presumptive evidence 

 as to the causal relationship of the amoebae, and practically con- 

 clusive evidence is afforded by animal exjjeriments. Dysentery 

 occurs occasionally in animals, e.g. in monkeys, but it is. of 

 comparatively rare occurrence. The disease sometimes results 

 in the dog by experimental inoculation with dysenteric material. 

 Kartulis, for example, records two cases, in one of which liver 

 abscess was present. Cats are, however, found to be more 

 susceptible, especially young animals. Dysenteric changes have 

 been produced in this animal by Kartulis, Kruse and Pasquale, 

 and others. The method generally adopted is the introduction 



