108 BRITISH FRESHWATER RHIZOPODA. 
reddish body is seen to form only the central region, 
which is surrounded by a colourless and hyaline border. 
Then the appearance of the organism is that of a 
colourless disc, with a granular, coloured mass occupy- 
ing ordinarily a central position, but sometimes 
posterior. The margin is homogeneous and structure- 
less, and is seen with difficulty, while the central 
coloured region is more or less sharply defined. The 
authors observed in the endoplasm a variable number 
of greenish-brown bodies which they regarded as more 
or less accumulated food-substances, of vegetable origin, 
becoming more reddish with the progress of digestion, 
and mingled with them were numerous vacuoles, which 
at times were difficult to be made out owing to the 
opacity of the body-substance. 
This organism sometimes exhibits a degree of 
mobility, occasioning variations of form and appear- 
ance, which renders it difficult of identification. Its 
progress being intercepted by any object, the disc-like 
body will double back upon itself, and the animal will 
set off in some other direction. This seems to be the 
habit represented by Schulze in his figures and descrip- 
tion of the organism which he named Plakopus ruber, 
but which there is little reason to doubt was the Hyalo- 
discus vubicundus of Hertwig and Lesser. 
According to Schulze one or more nuclei are present, 
not readily observable in the ordinary state, but under 
reagents becoming evident. A comparatively large 
nucleolus is surrounded by a clear round border, with 
its outer limits only seldom sharply marked. It is 
remarked also (referring to Plakopus ruber) that a 
variable number of different-sized pellucid vacuoles is 
scattered through the body-mass. This is character- 
istic of our Cheshire examples. The outer hyaline 
stratum is, under a high magnification, faintly granu- 
lated. 
The mode of reproduction of this organism has 
not been sufficiently studied. In all probability it is 
analogous to that of Vampyrella. 
