N. H. SWELLENGREBEL 
115 
(1908-9) is right in asserting that the possession of this double 
flagellum is not a generic character of Herpetomonas. Still there is 
some difficulty with I’espect to this matter: Patton and his co-workers 
regard the presence of the double flagellum as an early sign of division, 
but I sometimes found that the percentage of flagellates showing 
undoubted signs of division (of the nucleus or the blepharoplast) was 
larger among herpetomonads with one flagellum than among herpeto- 
monads with two flagella. Of 400 herpetomonads with only one 
flagellum, 23 showed two nuclei and 377 did not divide; on the other 
hand, 400 herpetomonads with two flagella did not show any other sign 
of division. Perhaps the possession of a double flagellum is a sign of 
division proceeding under unfavourable circumstances. 
The statements of different authors are not in agreement regarding 
the division of the flagellum: some assert that division results from 
longitudinal fission (Porter), others maintain that a new flagellum arises 
at the base of the old one (Berliner, Mackinnon). I have carefully 
studied this subject and have come to the following conclusions 
(Diagram IV). The first stage of the production of a new flagellum is 
represented in Diagram IV, Figs. 1-2. The marginal granule becomes 
larger and divides into two chromatic granules, united by an achromatic 
substance; one of these granules is directly connected with the old 
flagellum. 
The achromatic substance seems to be the continuation of the 
rhizoplast, and like this, it stains pinkish with Giemsa. In the next 
stages (Figs. 3-5) the rhizoplast shows longitudinal fission and the 
basal granule divides. There are now two rhizoplasts, one connected 
with the old flagellum, the other with the free marginal granule 
(Figs. 4-5). 
I am not sure whether the fission of the flagellum proceeds also in 
a direction opposite to that of the rhizoplast, because the two flagella 
remain entangled even when fully grown out. Some observations 
(Fig. 6) seem to prove, however, that the new flagellum becomes 
emancipated very early, and grows independently of the old one. 
Berliner has made a similar observation. The two flagella remain 
connected for a long time at the base by the achromatic substance 
already described (Diagram III, Fig. 3; Diagram IV, Fig. 6), which 
forms the delicate interflagellar membrane, mentioned by Prowazek; 
its presence accounts for the fact that sometimes the two flagella may 
remain entangled even when the two daughter-cells are nearly 
separated. 
Parasitology iv 
8 
