M. Koidzumi 
269 
described by Porter. The bands do not reach the posterior end, the hinder 
portion of the body being free from them. In some individuals, measuring 
some 20 /x in length, the anterior region provided with the bands is nearly 
equal to or rather larger than the posterior region which is destitute of them. 
As the animalcule grows larger, the bandless posterior portion is chiefly in¬ 
creased in size, so that in large individuals the anterior region is commonly 
but little larger than in small forms, while the posterior region is relatively 
very voluminous, its length measuring two, three, or more times that of the 
anterior region. 
It is from these spiral bands that the flagella arise, the basal granules of 
the flagella being situated in them. The flagella are rather conspicuous in 
this organism. They are shortest anteriorly and increase in length towards 
the posterior, the hindmost being some three times as long as the shortest 
at the anterior end. In large forms, measuring 30-40/x in length, the shortest 
flagella measure some 10 p, and the longest ones some 30/x, so that a large 
number of them pass over the hinder part of the body. In small forms the 
flagella are proportionally somewhat longer. The shortest flagella situated 
anteriorly are directed forwards and are swung vigorously. The longest ones, 
on the other hand, are directed backwards: they lie more or less closely on 
the surface of the body, and do not move so actively. 
The endoplasm seems less granular than in most other trichonymphids. 
It is remarkably viscid and a large amount of food debris is commonly found 
in the posterior region. The most remarkable character of this form is that 
it seems omnivorous, and not only wood fibres but other protozoa are found 
in the endoplasm, probably ingested as food. It is very common to see indi¬ 
viduals with their endoplasm gorged with organisms such as spirochaetes, 
small trichonymphids, or other flagellates, the shape of the body being some¬ 
times remarkably altered owing to the large size of the ingested organisms. 
The nucleus is situated near the anterior end. It is oval or round, measuring 
4-5 /x, or sometimes as much as 7 /x in diameter. It contains usually a pair of 
chromatic bodies, hanging from the anterior surface and suspended in the homo¬ 
geneous ground substance (PI. XIII, figs. 32-34). In the majority of cases, these 
chromatic bodies are club-shaped, and are independent of one another, hanging 
side by side. In some forms, however, their posterior ends or the greater part 
of them are fused together, so as to form, in extreme cases, a body of an oval 
shape, attached to the anterior wall of the nucleus by means of two mam¬ 
millary projections. The chromatic bodies usually stain very deeply and 
almost homogeneously, though in good preparations a more faintly stained 
ground substance with intensely stained granules embedded in it can be 
distinguished. The nucleus is surrounded by a dense and structureless sub¬ 
stance and is very distinct in its contour, though the membrane is not clearly 
recognizable. 
The nucleus is not suspended freely in the endoplasm, but is connected 
with the anterior tip of the body by means of a special structure. This is a 
