THE INTESTINAL PROTOZOA OF FROGS AND TOADS. 247 
The organism occurs in Rana esculenta captured in Rovel- 
lasca, Pavia, and Como. It is invariably present at all seasons 
and is sometimes very abundant. It was never found in 
toads. Regarding its structure, he says that an ectoplasm 
and endoplasm are distinguishable; that there is a round 
nucleus, with a nucleolus ; that the form of the body is very 
variable, the protoplasm being almost liquid ( “ scorre- 
volissimo quasi fosse liquido”). Movement is rapid and 
effected by the thrusting out of digitiform pseudopodia, 
which may also be thrust in and out, however, without the 
animal changing its position. No contractile vacuole was 
noticed. The dimensions are stated to be as follows: Dia- 
meter, when rounded, from 8 p to 24 4; when digitiform, up to 
30°3 win length ; diameter of nucleus never greater than 4°4 yu. 
Additional statements regarding the life-history have been 
made by Brass (2) and Hartmann (24). According to the 
former, the amcebe are able to reproduce by division, by 
formation of swarm-spores and by means of resting spores. 
According to the latter, an autogamy simular to that of 
Entameba coli occurs in Entamceba ranarum, though 
the observations upon which the statement rests are as yet 
unpublished. 
I will now give my own observations on the animal. ‘They 
differ in many respects from those of others. 
Regarding the host, I can state that HEntamcba 
ranarum occurs in Rana temporaria (Cambridge and 
Munich), Rana esculenta (Munich), and Bufo vulgaris 
(Cambridge). I have found it most frequently in Rana 
temporaria, about 23 per cent. of individuals examined 
being infected. Occasionally the parasite is present in 
immense numbers. It is also noticeable that the infection is 
local, for I often found that nearly all the frogs captured 
together in certain places were infected, whilst of others 
taken ina different area not one harboured the parasite. 
Whether the animal exercises any injurious effect upon its 
host or not must remain an open question. Certain it is, 
however, that sometimes when the parasites are numerous 
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