The early trophozoite, then, is a small circular cell embedded 
between the pyriform epithelial cells lining the stomach of the flea. 
As many as twenty-five may be found in one flea situated near the 
proventriculus, but occasionally near the pylorus. They are 
frequently found in pairs. These cells contain large refractile 
granules, and a readily staining nucleus. The whole cell stains before 
the stomach cells when the organ containing it is placed upon agar 
having an aniline dye in suspension. In clear specimens a slender 
process can be detected, by which the parasite is attached to the 
remains, probably, of its trophic cell that has been destroyed by it. 
The relation of this early form to the rostrated trophozoite next to be 
described is not merely conjectural, because it is only found in young 
infected fleas and in those containing older trophozoites which cannot 
be mistaken. Besides, the granules in all the early stages are very 
characteristic. The fact that these early forms are only found in 
young flea imagines makes it highly probable that this parasite is 
ingested by the larva, for in older fleas the more highly developed 
phases of sporogony only are to be found, and it is unusual to see 
parasites in other than contiguous stages in the same flea. The age 
of a flea may be roughly estimated by the degree of growth of the 
ova in the ovisacs in the females, and by the degree of development 
of the spermatozoa in the vesiculae seminales in the males. In the 
dog-flea the absence of spermatozoa in the spermatheca of the female 
IS a most certain evidence of the extreme youth of the imago, 
ecause fecundation by the male takes place very soon after the 
metamorphosis of the female is completed; and in the male the 
P rmatozoa within the vesiculae seminales are tied together by their 
“f*"' ‘he '"lago has hatched 
In ifsCTofvtfitdevelops a well-marked epimente 
epitheLl cell iT’' I ‘h‘“ 
lining membrane of'thri^LTch’' "‘rh epimeriteto th. 
the early stae-es hxr k • hody of the cell is divided, ir 
P•'otomerite‘and^h^deTtom^^f 
omerite. As the cel] grows it becomes 
