132 



in addition to the nuclei, a number of small refractile granules 

 of a substance known as volutin. The young cysts also contain 

 masses of glycogen. (See Fig. 38.) 



lodamceba. -- Nucleus vesicular with moderate-sized central 

 karyosome and well developed membrane without a distinct 

 peripheral zone of chromatin, but with a single layer of rather 

 large granules between the karyosome and the outer membrane; 

 cysts very characteristic, formerly known as Iodine cysts or I. 

 cysts, of very irregular shape, containing, besides a single nucleus, 

 a number of brightly refractile granules and a relatively large 

 clearly denned solid mass of glycogen which stains very deeply 

 in iodine. The nucleus is peculiar in that the karyosome comes 

 to lie peripherally in contact with the nuclear membrane. (See 

 Fig. 39.) 



Dientamceba. Mature individuals with two similar nuclei; 

 these are vesicular with a large central karyosome consisting of 

 a number of granules; nuclear membrane very delicate without 

 distinct peripheral chromatin; cysts not found. (See Fig. 40.) 



Intestinal Amebae 



The intestinal amebse of man, according to Dobell, consist 

 of Endamceba histolytica, E. coli, Endolimax nana, lodamceba 

 butschlii jud Dientamceba fragilis, and to these must be added 

 Councilmania lafleuri recently described by Kofoid and Swezy. 

 A number of other species have been described by various writers, 

 but these have probably been either deteriorated examples of the 

 known species, body cells mistaken for amebse, or a confusion of 

 two other organisms. The discovery by Craig of an intestinal 

 ameba having a flagellated stage, and now known as Craigia hom- 

 inis, and the discovery of an allied species, Craigia migrans, by 

 Barlow, have not been corroborated by other workers, and, as 

 Dobell has pointed out, these organisms are probably in reality a 

 mixture of known amebse and flagellates. A number of species of 

 free-living amebse are occasionally found in fseces of human beings, 

 apparently being able to pass through the digestive tract uninjured, 

 but unable to thrive there. These amebse are usually placed in the 

 genus Vahlkampfia, in which there is not a flagellated stage in the 

 development. Another species of Sarcodina occasionally found 

 in human fseces is Chlamydophrys stercorea. This is a common 



