A PARASITE OF THE HUMAN FLEA 51 



are aided in separating by the active lashing move- 

 ments of their flagella, and organisms, looking succes- 



FIG. 10 CRITHIDIA PULICIS : FLAGELLATES 



A, Young form; B, older form; C, full-grown form, showing 

 well-marked membrane with myonemes 



sively like an opening pair of scissors, a Y, and an 

 enormous individual with a flagellum at each end, 

 are encountered. If the latter be watched carefully, 



