682 Dysentery 



Losch was the first to observe that quinin was destructive to in- 

 testinal amebas, and his observations have been reviewed by many 

 others. Musgrave and Clegg found that active cultures of one 

 ameba were killed in ten minutes by a i : 25000 solution of quinin 

 hydrochlorate. The exposed organisms quickly encysted themselves 

 and in from five to eight minutes many of them had broken up and 

 disappeared. After ten minutes all were dead. Cultures of another 

 ameba similarly treated gave a scanty growth after ten minutes. 



Vedder found that emetin would kill ameba in dilutions up to 

 1:100,000, and Rogers has shown that this drug is the most de- 

 structive agent we possess as an amebicide. Unfortunately it does 

 not kill the encysted forms. 



Exposure to 1:1000 solution of formalin did not kill encysted 

 amebas in twenty-four hours. Acetozone did not kill amebas in 

 I :iooo dilutions. If, however, the acetozone was made i per cent, 

 acid to phenolphthalein the amebas were all kil'ed by i ; 5000 solu- 

 tions in ten minutes. 



Metabolic Products. — It seems as though Entamoeba histolytica 

 must produce some metabolic product that exerts an enzymic ac- 

 tion upon the human tissues and thus accounts for the destructive 

 nature of the lesions. This has not, however, been demonstrated 

 as yet. 



G. Fully developed cyst of Entamoeba tetragena containing four nuclei and 



one mass of chromatin. 

 //. Illustrating the type of nucleus as observed in Entamoeba tetragena in 



specimens stained with Giemsa stain. 

 Lower Group. — Amceba lobospinosa stained with Delafield's hematoxylin after 



fixation with sublimate alcohol. 

 I, 2, and 3. Vegetative organisms showing the large contractile vacuole and 



the typical nucleus containing a deeply stained karyosome almost 



filling the nucleus. 



4. A vegetative ameba in which the nucleus has divided. 



5, 6. Vegetative amebse in which the nucleus is dividing. Polar bodies 



are present connected by filaments and a well-marked equatorial 

 plate is apparent. 



7. Degenerated vegetative ameba filled with vacuoles and with atypically 



staining nucleus. 



8. Amceba lobospinosa containing a protozoan organism. These forms 



have been mistaken for sporulating amebae. 



9 and 10. Encysted forms of Amoeba lobospinosa during the first few 

 days in cultures. 



II to i8 (except 14). Various cystic forms of Amoeba lobospinosa show- 

 ing the character of the cyst wall in the older cysts. At 12 the cyst 

 contains two vacuoles and the cyst membrane is folded in, an appear- 

 ance frequently observed in cultures which have become dry; 15 and 

 1 7 represent cysts in which the cyst wall is cracked and a nucleus can- 

 not be distinguished; 16 represents a cyst filled with deeply staining 

 granules of chromatin derived from the degenerated nucleus; 18 is a 

 cyst in which only the cystic membrane is visible, the ameba having 

 escaped from the cyst. 



14. A fragmenting ameba frequently mistaken for a budding organism before 

 the separation of the fragments (Charles F. Craig, M. D., in Journal 

 of Medical Research, vol. xxvi. No. i, April, 1912). 



