In three cases of poliomyelitis acuta which were investigated by Ellermann, the spinal fluid obtained by puncture of the cord contained bodies, from 10 µ to 15 µ in size, which had amœboid movements and exhibited variously shaped pseudopodia in large numbers. After staining, a usually excentric nucleus, about 1·5 µ in size, was demonstrated in them. Order. *Foraminifera*, d’Orbigny. The order is divided by Max Schultze into Monothalamia and Polythalamia. Only a few of the former can be considered here. Sub-Order. *Monothalamia.* (Testaceous Amœbæ). These forms occur frequently in fresh water, rarely in sea water. They possess a shell which is either pseudo-chitinous in character, or consists of foreign particles, or in a few cases is composed of siliceous lamellæ. There is usually an orifice for the protrusion of pseudopodia. The only representative of the order of interest here is:-- Genus. *Chlamydophrys*, Cienkowski, 1876. The genus is based on a form which A. Schneider carefully investigated and considered to be the _Difflugia enchelys_ of Ehrenberg. L. Cienkowski rediscovered this same form and created for it the genus _Chlamydophrys_. We agree with this view, but not with the renaming of the organism (so common at the time). If the parasite in dung, _Chlamydophrys stercorea_ Cienk. is identical with _Difflugia enchelys_ of Ehrenberg, the old specific name should be retained. The genus is characterized by the possession of a hyaline, structureless, slightly flexible shell which is ovoid or reniform. At the more pointed pole there is an orifice situated terminally or somewhat laterally, serving for the emergence of the filiform pseudopodia (fig. 13, _a_). The protoplasm does not entirely fill the interior of the shell. An equatorial zone bearing excretory granules divides the shell internally into two almost equal portions. The anterior portion is rich in vacuoles and serves for the reception of nutriment and for digestion. The posterior part is vitreous, and contains the nucleus. One to three contractile vacuoles are situated in the equatorial zone. *Chlamydophrys enchelys*, Ehrbg. Syn.: _Chlamydophrys stercorea_, L. Cienkowski. This species (fig. 13) is found in the fæces of various animals (cattle, rabbits, mice, and lizards), and also in quite fresh human fæces. According to Schaudinn, the parasite occurs so frequently in the human fæces that it must be considered of wide distribution. The species must traverse the intestine of man and animals during one stage of its life cycle, as Schaudinn showed by experiments on himself and on mice. He infected himself with cysts (fig. 14) by swallowing them, and evacuated the first _Chlamydophrys_ as early as the following day. After the evacuation of numerous specimens on one of the following days the infection ceased.