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Herpetomonas and Crithidia 
iodine after staining with Giemsa’s solution, so these granules consist of 
volutin, a substance found already in trypanosomes and other Protozoa 
(Swellengrebel, 1910; Hindle, 1910). I have never seen the axial 
filament described by Prowazek, but sometimes an uncoloured spirally- 
wound line may be seen passing through the cell (Diagram III, Fig. 6). 
Similar structures have been mentioned by Miss Porter. 
The base of the flagellum is a very complicated structure 
(Diagram IV, Fig. 7). Often a distinct basal granule is to be seen and 
another thickening of the flagellum is present at the point where it 
becomes free. This latter granule has been described by Berliner 
(1909); I propose to call it the “marginal granule.” Between these 
Diagram IV. Production of a new flagellum in Herpetomonas calliphorae. 
1-2. Fission of the marginal granule ; in Fig. 2 the basal granule is distinct. 
3. Fission continues along the rhizoplast. 
4-5. The basal granule is also divided. 
0. This figure suggests that the new external flagellum is not produced by fission of the 
old one, but by independent growth. 
7. Two new flagella are produced each showing distinct basal and marginal granules. 
two granules (basal and marginal) is situated that part of the flagellum, 
which is generally called “ rhizoplast ”; it stains pinkish with Giemsa, 
whereas the rest of the flagellum stains crimson. 
Herpetomonads are frequently found which possess two flagella 
without showing any sign of division; as, however, in other flies similar 
flagellates may be found with only one flagellum, I think Patton 
