676 Dysentery 



Relationship of the Organisms. — In recent years (1910-1915) 

 much morphological and experimental study of these amoebas has 

 been conducted with results that are given in full, together with the 

 literature, in a paper " The Identity of Entamoeba Histolytica and 

 Entamoeba Tetragena, with Observations upon the Morphology and 

 Life Cycle of Entamoeba Histolytica" by Charles F. Craig.* The 

 results of his studies, as set forth in the paper, go to show that 

 Schaudinn was in error in regard to the developmental cycle of 

 Entamoeba histolytica, that what he supposed to be its sole method 

 of reproduction, is only that means that preponderates during the 

 period of its greatest activity; that as the acme of the dysenteric 

 disease is passed and the process of repair sets in, the other mode of 

 reproduction characteristic of Entamoeba tetragena is observed, 

 and that the two species Entamoeba histolytica and Entamoeba 

 tetragena are one. There is, therefore, to all appearances, and 

 according to the best information available at present, only one 

 pathogenic intestinal- amoeba, the Entamoeba histolytica. The 

 same conclusions have also been arrived at by Darling, f 



With regard to Entomoeba coli, opinion as to its non-pathogenic 

 disposition is much less certain than a few years ago. Williams and 

 Calkins J close their excellent paper upon "Cultural Amoeba; a 

 Study in Variation' ' with the statement that " it is unwise for any- 

 one at present to be too positive in regard to the distinctive features 

 of Entamoeba coH, E. tetragena and E. histolytica, or any of the 

 Entamoeba groups. There may be in man, three or more, or two 

 (as Hartmann, Whitman, Walker and Craig now think) or possibly 

 only one species of ameba manifesting different forms under different 

 conditions." 



Isolation and Cultivation. — Many experimenters have made 

 more or less successful attempts to cultivate amebas. Musgrave and 

 Clegg,§ whose interesting paper the student will do well to read, and 

 in which he will find a complete review of all antecedent work, were 

 able to cultivate a considerable variety of amebas upon agar-agar 

 made of: 



Agar 20.0 grams 



Sodium chlorid 0.3-0.5 " 



•Extract of beef 0.3-0.5 " 



Water 1000. o cc. 



Prepare as ordinary culture agar, and render i per cent, alkaline to phenol- 

 phthalein. The finished medium is poured into Petri dishes. To obtain the 

 greatest number of most active amebas the patient should be given a dose of a 

 saline purgative, and the fluid evacuation resulting from its action employed for 

 inoculating the media. The cultures are, naturally, not pure; they contain 

 various amebas and numerous bacteria. 



* "Jour. Infectious Diseases," 1913, xiii, 30. 



t "Trans, of the Fifteenth International Congress on Hygiene and Dermo- 

 graphy," Washington, D. C, Sept., 1912. 



t "Jour Med. Research," 1913-1914, xxiv, 43. 



§ "Department of the Interior, Bureau of Government Laboratories, Biological 

 Laboratory," Manila, Oct., 1904, No. 8. 



