PATHOGENIC PROTOZOA. 415 



spore grows larger and larger, and finally the nucleus and the 

 vacuole make their appearance. The spores probably contain 

 cromatin granules. No sexual process was observed. 



Methods of Making Permanent Preparations. Prepara- 

 tions may be obtained by applying a perfectly cleaned cover- 

 glass to the Petri dish culture, and dropping it at once 

 into fixing fluid, but a better way is to drop a hanging plate 

 culture into the fixing fluid. The hanging plate must in this 

 case have been prepared on a very clean cover-glass, or it 

 must have been made on cover-glasses which have been 

 covered with a very thin layer of egg albumen before the agar 

 is spread on it, otherwise the film is apt to become detached. 

 The stain recommended specially by Walker is Mallory's 

 chloride of iron hematoxylin.* 



From various sources Walker obtained 44 different cultures 

 which he separates into 10 distinct species using as criteria 

 the characters of the ameboid, the encysted, and the sporu- 

 lating stages. A. coli Loesch (man) ; A. hominis sp. n. (man) ; 

 A. copayae sp. n. (guinea-pig) ; A. musculi sp. n. (house mouse) ; 

 A. gallopavonis sp. n. (turkey); A. ranas sp. n. (frog); A. 

 muris Grassi (mouse and rat); A.-intestinalis sp. n. (various 

 animals) ; A. enterica sp. n. (various animals) ; A. fecalis sp. n. 

 (wide range of hosts). 



Ameba coli Loesch has a number of synonyms. It is the organism described 

 by Councilman and Lafleur as A. dysenteriae and taken by them and many 

 others to be the cause of amebic dysentery. 



Ameboid stage, circular in outline when at rest; oblong, ligulate, or irregular 

 when in motion; size 9-20 mikrons when in resting stage; pseudopodium 

 normally single, lobose; ectoplasm, hyaline, apparently only in the pseudo- 

 podium; entoplasm finely granular; nucleus circular or oval, plastic, 3-5 mikrons, 

 surrounded by a narrow halo; vacuoles one to several, non -contractile. Encysted 

 stage appearing late and slowly in cultures; cysts circular, 6-9 mikrons; wall 

 single, double contoured, regular; contents finely granular; nucleus not visible. 

 Sporulation not frequent; spores never numerous, spheroidal .7-2 mikrons. 

 Movement rather active. Habitat, intestinal tract of man. 



Ameba cobaya Walker. Ameboid stage circular when at rest, oval, oblong, 

 ligulate, less frequently irregular, when in motion; 15.5-25 mikrons in the resting 

 condition; pseudopodium normally single, lobose; ectoplasm, hyaline extensive; 

 entoplasm coarsely granular; nucleus circular but plastic, surrounded by a 



* Mallory and Wright. Pathological Technic. 1904. 



