272 WALKER. 



nuclear membrane, with or without a minute karyosome or a few scattered 

 fragments in the nuclear-network. This variety corresponds with the 

 histolytica species of Schaudinn (fig. 12). In the second vaiiety the 

 chromatin is rather more abundant and is arranged in part as a loose 

 granular layer, that frequently shows radial projections, about the inner 

 surface of the nuclear membrane, and in part as a loose central karyosome 

 which, in its most typical form, consists of a minute centriol surrounded 

 by an achromatic halo that is bounded by a circle of chromatin granules. 

 This variety corresponds with the tetragina species of Viereck and Hart- 

 mann (fig. 13). 



During the active phase of amoebic dysenterj'' only the trophozoites 

 of these entamoebse are present in the stools. With aqueous alum hema- 

 toxylin, which is an extremely precise stain for the chromatin of enta- 

 moebse, only stages of binary fission have been observed. I have been 

 unable to find any of the chromidial stages that are said by Schaudinn, 

 Craig and Hartmann to precede the formation of spores in Entamoeba 

 histolytica. It seems possible that the use of iron hematoxylin or other 

 less precise chromatin stains may have resulted in mistaking bacteria or 

 protoplasmic granules for chromatin. I have not observed any of the 

 later stages of the formation of the spores or the free spores in either 

 fresh or stained preparations. 



When the acute symptoms in untreated dysentery have passed and the 

 stools of the patient are becoming normal the trophozoites become smaller, 

 less actively motile and more rounded in the resting forms, and the 

 chromatin becomes more abundant in the nucleus. These changes are 

 preparatory to the development of the cysts. Such forms resemble the 

 m.inuia species of Elmassian (fig. 14). Finally, encysted forms contain- 

 ing 4 nuclei appear which may persist for an indefinite period or until 

 the patient suffers an exacerbation of the acute symptoms.' Thus in 

 amoebic dysentery 6,442 there appeared in the stools on January 30, 1911, 

 a considerable amount of mucus and pus streaked with blood. On Jan- 

 uary 31 the stools were partly formed and partly fluid, consisting of 

 mucus, pus, and blood and containing many amceboids, resting and 

 encysting entamcebse. The amoeboid and resting entamoebge were small 

 but with the histolytica type of nucleus, the encysted forms were the cysts 

 of the tetragina type containing 4 nuclei. The symptoms abated without 

 treatment, the stools became normal, and the patient has had no recurrence 

 of the disease; but the cysts containing 4 nuclei have persisted in the 

 stools up to the present time (August 23, 1911). Still more instructive 

 is the following chronic case, amoebic dysentery 5,748, which came down 

 with a typical attack of amoebic dysentery on April 29, 1911, with mucus, 

 pus, and bloody stools containing many large entamoebas of the histolytica 

 type (fig. 12). The patient was put under treatment to which he 

 promptly responded, the symptoms abated and the stools became normal. 



