160 PROTOZOAN PARASITISM 



from an exudate of an active gingivitis, it is exceed- 

 ingly active, swimming dartingly about, with fla- 

 gella and undulating membrane at high speed, twist- 

 ing and turning, or becoming anchored caudally for 

 a moment, while its peripheral organelles lash and 

 undulate, threshing solid particles about in a violent 

 fashion, then pulling loose from an attenuated 

 anchoring appendage and swimming rapidly on its 

 way. Nothing more than its darting motion and its 

 possession of flagella and undulating membrane may 

 be made out of active specimens. As it slows down 

 from cooling or exposure the "whip-cracking" ryth- 

 mic lashing of flagella synchronous with the undulat- 

 ing membrane waves, the propulsion of bacteria 

 against the ingesting surface, the flexibility of the 

 body, the axostyle, and the revolving of the body in 

 forward motion may be seen. 



It has four anterior flagella, which with the free 

 margin and the basal fiber of the undulating mem- 

 brane, and the stiff, posteriorly protruding axostyle, 

 originate from the blepharoplast, within a knobbed 

 anterior pole, which is the base of movement of the 

 motor organelles. The posterior and inner part of 

 the body may be seen to be vacuolated and to con- 

 tain granules, bacteria. The nucleus is not seen in 

 the unstained specimen. 



Staining by Heidenhain's iron-haematoxylon 

 method brings out the nucleus and the structural 

 detail. Very pretty specimens may be made with 

 Wright's or Leishman's blood film stains, by care- 



