SARCODINA 



1051 



which have been cultivated on agar, and for this genus Chatton (1912) 

 has proposed the name Valilkampfia. They are small organisms, 

 5 to 30 microns in diameter, provided with fingerlike or spinous pseu- 

 dopodia, and characterized by a nucleus witli a large karyosome and 

 a single nucleated resistance cyst in which no multiplication occurs. 

 They have repeatedly been cultivated from human dysenteric stools, 

 from the air, and apparently from liver abscess pus. It has been 

 shown, beyond doubt, that they are harmless to man, and that they 

 pass through the intestinal tract with food and water in the cyst 



FIG. 120. ENTAMBGEA HISTOLYTICA. Vegetative form showing histolytica type of 

 nucleus. Stained with iron hematoxylin. (Army Medical School Collection, 

 Washington, D. C.) 



form. While they will develop in cultures at body temperature, a 

 better growth is obtained at the temperature of the room. Since 

 the true parasitic amoeba? have never been cultivated on artificial 

 media, the Vahlkampfia may be dismissed with the statement that 

 they are not pathogenic. 



The genus Entamoebse includes all human parasitic forms, and is 

 characterized, among other things, by the absence of a contractile 

 vacuole, which is always present in Amo?ba and Vahlkampfia. The 



