Parasites of Frogs and Toads. 
431 
of the organism. From these two chromatic granules at the 
posterior extremities of the axial rods spring the posterior 
flagella, which may attain a length equal to three times that 
of the body. 
Very minute forms of this parasite are sometimes found — not 
reaching a greater length than 2 — Sy. The nucleus is usually 
less complex in these. 
Multiplication appears to take place by means of longitudinal 
division, but is very difficult to observe. 
Cysts of an oval shape are also found by Octomitus. From 
these cysts a single monad subsequently escapes. 
No sexual process has been observed. 
(4) Monocercomonas bufonis n. sp. 
By this name I propose to designate a new 4-flagellate parasite 
which inhabits (on rare occasions) the large intestine of the toad. 
It is of an oval shape, with a large, rounded nucleus and four 
anteriorly-directed flagella. In length it measures about 15//,. 
Details of the life-cycle have not been discovered. 
B. Amoebae. 
Two amoeboid organisms have come under my observation — 
one which appears to be a stage in the life-history of Chlamy- 
dophrys stercorea Cienkowski, and another which I may call 
Entamoeba ranarum Grassi, though it is by no means certain that 
Grassi really observed this organism. 
The smallest forms of this amoeba are not more than 3 — oy 
in diameter, and are characterised by possessing a small ring- 
shaped nucleus with a central chromatic granule (karyosome). 
As they increase in size, the amoebae lose the former character of 
their nucleus, and come to possess a nucleus without a karyosome, 
and with chromatin granules evenly distributed throughout. At 
the periphery, however, larger granules are always present, so 
that the nucleus preserves its annular appearance. There is no 
contractile vacuole. The amoebae divide in the frog’s gut, the 
nuclei dividing by a kind of very primitive mitosis. Although 
stages in division are very hard to obtain, the amoebae must 
divide with considerable rapidity, for frogs are occasionally found 
harbouring great numbers of the parasite. 
The small amoebae, which continue to divide, appear to be 
capable of encysting : but the large actively-feeding animals — 
which may reach a diameter of 60//. or more — seem to lose the 
power of encysting, and always appear to degenerate and die. 
The nuclei of these large forms also undergo changes 
Before encystment, the nucleus of the amoeba develops a 
