290 
Intestinal Protozoa in Termites 
and D. parva) it is very indistinct and hardly visible in the majority of indi¬ 
viduals, except at the anterior end—probably owing to its slenderness. 
Just as in Pyrsonympha, the anterior tip of the axial filament is situated 
at the anterior tip of the body, and the flagellar cords arise at this point. In 
well-developed axial filaments, the anterior end is often slightly thickened, 
and two parts are then distinguishable at this end; namely, a main central 
portion, which is faintly stained, and a peripheral zone which stains intensely. 
The mode of arrangement of the flagellar cords on the surface of the body 
differs from that in Pyrsonympha. The cords run parallel with the longitudinal 
axis of the body, and their distribution is not uniform over the entire surface, 
but is limited to one-half of the surface or a little more. It is on the surface 
occupying the outside in the spirally curled body that the flagellar cords are 
found, the surface occupying the inside being destitute of them. The flagellar 
cords are straight in their course, those of only one species, viz. D. rugosa, 
forming an exception, where they are fairly wavy. In the majority of the 
species, each cord is situated on a distinct ridge, so that the outline of the 
organism appears beautifully serrated; but in a few species the ridges are 
absent or very indistinct, and the surface appears entirely or almost smooth. 
The surface destitute of cords is smooth in all species. The free portions of 
the flagellar cords at the posterior end of the body commonly measure from 
one-fifth to one-fourth of the body length, except in one species ( D. leidyi) 
where they are conspicuously long. 
In some species the body is entirely naked, while in many others peculiar 
filamentous appendages, such as are seen in Holomastigotoides and Pyrso¬ 
nympha, are found on it. In some forms these appendages are present in 
large numbers, and are distributed over the greater portion of the surface of 
the body, while in others they are limited to a small area. Their mode of 
distribution on the body is rather regular, and in one form they are arranged 
in very regular transverse rings. The nature of these filamentous structures 
will be considered afterwards. 
The nucleus is situated at the anterior end, except in one species ( D. rugosa), 
in which it is found in the middle portion of the body. In one other species 
( D. exilis) individuals with a terminal nucleus and those with it separated 
from the anterior end are both common. I am not sure whether or not such 
individuals are ever to be seen in the other species. The internal structure of 
the nucleus is of the same type as that of Pyrsonympha. When situated at 
the anterior end of the body, it is oval or piriform. In the majority of forms 
its posterior end is rounded, whilst it narrows towards the anterior pole. The 
narrowed end of the nucleus is usually found at the extreme anterior end of 
the body, where the anterior tip of the axial filament is also fixed. From this 
disposition, it cannot be doubted that the nucleus and the axial filament are 
kept in connexion with each other, just as in the forms of Pyrsonympha. The 
nucleus when localized at the middle region appears commonly round, but one 
peaked point is often distinctly noticeable (PI. XV, fig. 72) which may be taken 
