282 
Intestinal Protozoa in Termites 
and the mature ones invariably swim freely in its cavity. It is also the case 
in our forms that most individuals attached to the wall appear to be small, 
but attached individuals of large size are also found quite commonly. It is 
by no means rare, moreover, to find small forms swimming freely in the cavity 
of the gut. In the club-shaped forms hanging from the wall, the body is almost 
straight or slightly curved, but the course of the flagellar cords on the body 
wall is distinctly spiral, indicating clearly that the body is twisted in various 
degrees. In the forms living freely in the intestinal cavity, the body is not 
only twisted but also spirally wound as a whole. Forms hanging from the 
wall do not remain quiet, but continue to move gently. Free-swimming forms 
usually display vigorous motions; and though they do not change their position 
markedly, the anterior portion is commonly swung very actively in all direc¬ 
tions. 
The dimensions also vary considerably in this species. Individuals measure 
usually 40-150 p, occasionally as much as 170 p, in length, and 19-40 p, some¬ 
times up to 50/x, in breadth. According to Leidy (1881), Pyrsonympha vertens 
measures 100-160/x in length, but Porter describes specimens attaining a 
length of 275 g and more. Comes (1910 a, 1912) and Grassi (1893, 1911) give 
no measurements of their forms, whilst Zulueta (1915) states that his species 
(called “ Dinenympha gracilis Leidy,” but really a Pyrsonympha) measures 
from 18 g to 90 g or more. 
The axial filament is very well-developed in this species. It hangs from the 
anterior end of the body in the endoplasm and lies quite free from the body 
wall throughout its entire length. It is thick, and oval or elliptical in cross 
section at the anterior portion. Towards the posterior end, it becomes gradually 
thinner and slender. Its posterior extremity is not connected with any part 
of the body wall, but ends freely in the endoplasm. In young individuals, 
the filament is slender and stains homogeneously with iron-haematoxylin and 
also with eosin. In large forms, however, it is thick at the anterior portion, and 
the posterior is usually found split into two, three, or sometimes more, slender 
filaments (PI. XIV, figs. 54 and 55). The anterior portion of the thick filament 
is commonly not homogeneous, and a deeply stainable wall and somewhat 
feebly stainable contents are distinguishable, though the boundary between 
these parts is indistinct. In some individuals a small portion at the anterior 
extremity shows an appearance as if consisting of several slender cords, 
taking dyes intensely, arranged regularly on the surface of a rod staining 
very faintly (PI. XIV, fig. 57). 
As regards the axial filament, some differences are recognizable between 
our forms and the American ones. The filament does not end freely at its 
posterior extremity in the American forms, but is fixed at the hind end of 
the body; and it seems, moreover, to remain simple, never splitting even in 
the later stages of growth. 
In Pyrsonympha grandis the anterior extremity of the axial filament is 
more or less abruptly pointed, and it is at this pointed extremity that the 
