1921J Kofoid-Swezy: Councilmania lafleuri 173 



periphery at one time, but usually one of these is advancing and the 

 others withdrawing. 



One of the most noticeable features in connection with the pseudo- 

 podia of this amoeba is the expulsive suddenness of their formation. 

 They are shot out almost instantaneously for the greater part of their 

 length while the remaining extension and peripheral modifications 

 proceed more leisurely. Invasion by the endoplasm is less rapid than 

 pseudopodial formation. In the event of change of direction of loco- 

 motion the withdrawal of the pseudopodium is relatively very slow. 

 The suddenness and rapidity of formation of the pseudopodia is the 

 most striking feature of the free stage of this very active amoeba. 



THE FREE AMOEBA 



Plates 18-20, figures 1-17 



The normal free stage of Councilmania lafleuri occurs in diarrheie 

 and dysenteric stools and in liquid stools after a saline purge and 

 sometimes in strands of bloody mucus on formed stools. It is rounded 

 up in cold stools, and when extended becomes sluggish with the drop 

 in temperature. In rare instances formation of pseudopodia may 

 continue for as long as thirty minutes in ordinary smears without the 

 warm stage. 



The ectoplasm of Councihnania is most evident in the clear hyaline 

 pseudopodia. Over the remainder of the body it forms a scarcely 

 visible peripheral tilm. In life the ectoplasm of the pseudopodia ap- 

 pears wholly structureless. In stained preparations it is often some- 

 what chromophile in the pseudopodia in iron haematoxylin and destains 

 slowly, exhibiting a dense homogeneous substance of fine texture quite 

 distinct from the granular and vacuolated endoplasm (pi. 18, fig. 4). 

 In some amoebae the ectoplasm destains wholly in the pseudopodia 

 or in their peripheral parts. In rounded-up individuals the ectoplasm 

 forms only a thin peripheral film, although in certain individuals 

 which seem to belong to Councilmania, from their nuclear structure, 

 there is a wide, vacuolated, clear zone in the periphery. 



The pseudopodia of Councilmania differ from those of Endamoeha 

 coli in being free from coarsely granular, vacuolated endoplasm, and 

 from those of E. dysenferiae in being perhaps rather smaller, restricted 

 as a rule, in the active state, to a smaller part of the periphery, and 

 in the expulsive suddenness of their formation. They are also some- 

 times more chromophile. 



