286 The Philippine Journal of Science ms 



Entamoeba coli, we believe that we are justified in the conclu- 

 sions that Entamoeba coli, unlike the Amo&bse, is an obligatory- 

 parasite and cannot be cultivated on Musgrave and Clegg's 

 medium, and that it is nonpathogenic and consequently plays 

 no role in the etiology of entamoebic dysentery. 



PART IV. FEEDING EXPERIMENT WITH "ENTAMOEBA TETRA- 

 GENA" AND ENTAM(EBA HISTOLYTICA 



By Ernest Linwood Walker 



Of the identified species of Entamoeba, 3, Entamoeba histolytica 

 Schaudinn, '^Entamoeba tetragena" Viereck, and "Entamoeba mi- 

 nuta" Elmassian, have been found associated with endemic trop- 

 ical dysentery and have been definitely implicated in the etiology 

 of this disease. 



Entamoeba histolytica was first described by Schaudinn in 

 cases of dysentery from Egypt, China, and Siam in 1903. It 

 is distinguished, according to this author, by its morphology and 

 its developmental cycle. This entamoeba possesses a distinct, 

 refractive ectoplasm and a granular, vacuolated entoplasm. The 

 nucleus is scarcely visible in the living entamoeba, is eccentric 

 in position, is frequently deformed by the movements of the enta- 

 moeba, possesses no limiting membrane, and is poor in chromatin, 

 which is arranged chiefly about the periphery. Entamoeba his- 

 tolytica, according to Schaudinn, does not become encysted in 

 toto and undergo schizogony within the cyst, as does Enta- 

 moeba coli; instead, there are developed small peripheral buds, 

 containing chromidia derived from the nucleus, which are con- 

 stricted off from the parent entamoeba and become surrounded 

 by a resistant capsule. 



Of the numerous feeding experiments that have been made 

 upon animals, in the following only has Entamoeba histolytica 

 been specifically identified : 



Schaudinn (1903) produced a typical dysentery in 3 cats with charac- 

 teristic lesions and entamoeba in the bloody mucous stool by feeding a dys- 

 enteric stool containing Entamceba histolytica. 



Craig (1905) produced dysentery in 50 per cent of the kittens injected 

 rectally and in 66 per cent of 8 kittens fed dysenteric stools containing 

 EntamcBha histolytica. At necropsy, typical lesions were observed, and 

 on section Entamceba histolytica was found in the tissues. 



Shirota (1912) was able to produce a dysentery, having the same lesions 

 as in man and with Entamceba histolytica in the stools and lesions, by intro- 

 ducing the stools of a human dysenteric patient into the rectum of young 

 cats. The bacteria isolated in cultures from the same dysenteric fasces, 

 when introduced into the rectum of other kittens, produced no clinical symp- 

 toms or pathological changes. 



