28 
these terms have been used, often more or less 
indiscriminately, to denote a type which, in the 
elongated, monadine form, has typically the kine- 
tonucleus near the anterior end of the body and 
well separated from the trophonucleus, and concur- 
rently, the flagellum springing directly from the 
anterior end of the body, becoming at once free; it 
follows from this that there is no trace of a mem- 
brane, the flagellum being connected with the body 
only by a short rhizoplastic portion. Herpetomonas 
muscae-domesticae, the type-species of this genus, 
was considered by Prowazek and others to pos- 
sess a double flagellum (i. e. to be biflagellate) ; the 
species of Leptomonas, on the other hand, have only a 
single flagellum. Occurringassociated with H. m.-d. 
AL. 
= 
2,7 
Fig. 1. Scheme illustrating the relationships of the different types discussed in the 
text. (For the sake of completeness it may be added that the figures of Leptomonas 
would serve also for Leishmania.) 
L = Leptomonas; H = Herpetomonas; C = Crithidia; T = Trypanosoma. 1, lepto- 
monad form; g, haptomonad (so-called gregariniform) phase for attachment, pos- 
sessed by all four types; A, herpetomonad form; and kl, leptomonad form of the 
Herpetomonas. (The distinction between these two phases is chiefly one of size and 
precocious division of the flagellum and is probably not so manifest in many cases.) 
he, crithidial (or “erithidiform’”’) phase of H.; ht, herpetotrypaniform phase (“try- 
panoid”); e, crithidial form (or “trypanomonad” in the case of Trypanosoma); sl, 
semi-leptomonad phase of Crithidia or Trypanosoma; t, trypaniform phase of 7. 
