A. Porter 
375 
development of the flagellum from the cyst or post-flagellate form— 
living material, and not stained preparations, being the basis of observa¬ 
tions. In H. jaculum the condition of the organism with the single 
flagellum is the normal one, and the double flagellum (PI. V, Figs. 
37, 38) is to be associated with division, as it is in the case of the 
Grithidia, Trypanosomes and Spirochaetes. I have never seen the 
origin of the “second flagellum” by a process of sprouting, such as 
Berliner 1 (1.909) describes. 
Though I have very carefully searched for rhizoplasts and diplosomes 
such as Berliner figured in H. jaculum, I have never found a single 
specimen showing this feature, no matter what stain and what magnifi¬ 
cation was used. 
The flagellum always was continuous and tapered gradually from its 
origin near the basal granule to its free extremity (PL V, Figs. 34, 36). 
A very slight thickening is occasionally present (Fig. 28) where 
the flagellum leaves the body, but this is the only indication of an 
anterior “diplosome” that I have ever seen, and it is my firm conviction 
that this structure as well as a rhizoplast is absent from the specimens 
of H. jaculum that I have examined. 
Regarding the exact nature of the flagellum, from a consideration of 
all its staining reactions, it would seem to consist largely of chromatin 
or a substance very closely allied thereto. If a cytoplasmic stain be 
used strongly ( e.g . orange-G or Lichtgriin) an extremely tenuous cyto¬ 
plasmic layer is seen around the chromatoid core. It is probable, then, 
that the flagellum of H. jaculum consists of a thin thread of chromatin 
with a film of cytoplasm around it. 
The Post-flagellate Stage. 
This phase of the parasite of H. jaculum is destined for the infection 
of uew hosts. Preceding the formation of the actual post-flagellate or 
cyst, the Herpetomonas often attach themselves to the wall of the gut 
or to debris. A doubly repeated longitudinal division of the adult 
parasite (PL V, Figs. 51—55) then occurs, during which the flagellum 
gradually disappears. The resulting individuals (Fig. 56) are very 
small, and are practically motionless. They consist of a nucleus and 
blepharoplast, together with a small amount of general cytoplasm. 
They gradually concentrate their bulk, a thin, gelatinous cyst wall that 
rapidly hardens is secreted around each, and they become small, oval 
1 My researches on H. jaculum were completed before Berliner’s account was published. 
