300 KOFOID AND SWEZY. 



vacuoles are of a different size (Fig. D, 3) the staining is differentiated, 

 the largest vacuoles are unstained, the smaller ones have a diffuse red 

 stain or a central darker red granule, and there is a tendency for the 

 stained granules to be most numerous posteriorly. In one case of 

 blob formation the stained vacuoles were all in the posterior lobe of 

 the cytoplasm. In addition to these stained particles there are others, 

 more numerous, of smaller size scattered in the cytoplasm about the 

 large vacuoles. By analogy with the digestive process in Paramecium 

 as demonstrated by the use of neutral red by Nirenstein (1905), the 

 indications are that the vacuoles are alkaline and that the small red 

 granules contain a tryptic ferment which in some of the less active, 

 rounded-up individuals may be represented by the diffuse pink stain 

 throughout the center of the cytoplasm. The larger vacuoles in 

 which this ferment has now dissolved take no stain, and after absorp- 

 tion their condensed alkaline remnants stain deeply. The aggrega- 

 tion of these smaller deeply stained granules in the posterior end is 

 suggestive of their ultimate disappearance in that region either by 

 absorption or by plasmecdysis. Their absorption is indicated by 

 vacuoles v\ith small stained granules in their centers. 



The conditions above described are indicative of the ingestion by 

 this organism of some form of alkaline liquid food from its host, 

 possibly of the dissolved proteids from the chyle as they come to the 

 mucous surfaces of the intestine on which the parasite has its habitat. 



The cytostome {cyt., Fig. B, and in most Figures on Plates 1-4) is a 

 broadly comma-shaped, hyaline area at the anterior end on the " ven- 

 tral" side opposite the undulating membrane. Its concave side abuts 

 against the nucleus and the head of the axostyle and its tapering 

 inner end extends somewhat beyond the nucleus. It is outlined by a 

 darker margin which anteriorly protrudes beyond the contour (PI. 1, 

 Fig. 4) of the body. 



The nucleus (??., Fig. B) is a spheroidal or ellipsoidal structure with 

 distinct membrane, usually more or less hidden by the enlarged ante- 

 rior end of the axostyle. It contains but little chromatin and this is 

 often massed in a single large, usually centrally located karyosome, 

 and in several or many minute granules scattered throughout the 

 nuclear fluid in a chromatin net (PI. 1, Fig. 3). 



The extranuclear motor apparatus consists of a structurally con- 

 tinuous unit, all parts of which are more or less deeply stained with 

 iron haematoxylin except the axostjde and the extra-cytoplasmic 

 flagella. The parts included in this unit, the flagella, axostyle, chro- 

 matic margin and chromatic basal rod of the undulating membrane 



