C. M. Wenyon 
337 
and the small oval forms with only a short flagellum or no flagellum 
whatever may be followed. 
During multiplication, therefore, the biflagellate appearance is the 
result of a very active multiplication of flagella, a multiplication which 
appears to lead the way in longitudinal division of this flagellate. The 
protoplasmic body of the flagellate is reluctant to divide so that it is 
always behindhand and has not completed its division till after the 
daughter flagella of the succeeding division have partially developed. 
When the daughter flagella of the succeeding division have partially 
formed the flagellate, as it were, realises its backwardness, and tries to 
regain lost ground by very rapid division. This latter fact accounts 
for the comparative rarity of such forms as that shown at fig. 14. 
The flagellate just described agrees with that of Prowazek in 
dimensions, and in most of the details of structure. The blepharoplast 
or achromatic structure near the kinetonucleus was not described by 
him, and I have failed to find the fibre which Prowazek traced through 
the body of the flagellate from its kinetonucleus. Flu has not figured 
this fibre. I think therd can be no doubt that the flagellate here de¬ 
scribed is Herpetovionas muscae domesticae, and is the same as that 
described by Prowazek and Flu. According to my observations this 
flagellate agrees in all essential points with the other flagellates so often 
described as Herpetomonas and is not a biflagellate as maintained by 
Prowazek and others. 
In addition to this large Herpetomonas a smaller one nray be found 
in some flies. It corresponds with the flagellate described by Flu as a 
Leptonionas. In reality it should be included in the same genus as the 
larger flagellate of the fly. It may be a distinct flagellate as Flu claims, 
or it may be a stage in the life history of Herpetomonas muscae 
domesticae. In some flies the small form alone is found. In others 
there is a mixed infection with the large and small forms. 
Still a third type of flagellate was found in some flies. These are 
shown in Text-figures 21-36. They occur mostly in the malpighian 
tirbes, but may also be found in the gut. They are remarkable in 
showing a trypanosome arrangement of the nuclear appai’atus. 
There is no free flagellum, but this organ terminates at one extremity 
of the body, the opposite extremity of the body being drawn out into a 
long tapering filament (figs. 25, 26, 30, 32). The nucleus is situated in 
the thicker part of the body and the kinetonucleus between it and the 
tapering extremity. The flp,gellum arises from a blepharoplast lying 
near the kinetonucleus (figs. 25, 26, 28, 30), and is continued past the 
