112 PROCEEDINGS OF THE ACADEMY OF [PaRT I 



The spherical body, 30 to ZS[i. in diameter (much larger than 

 Dim. mutans) is naked, but not smooth, owing to the presence of 

 numerous granules of a relatively large size, some of which project 

 a little outside the surface. Two layers, in fact, may be distin- 

 guished in the plasma, the ectoplasm with the above-mentioned 

 granular bodies, and the clearer endoplasm; but the difference be- 

 tween the two layers is here much less distinct than in typical Heli- 

 ozoa, those for instance which constitute the group of the Chalaro- 

 thoraca. Around the body, and radiating in every direction, but 

 less numerous anteriorly, are the pseudopodia, straight and very 

 fine, whose length attains to IJ^to 2 times the diameter of the body. 

 Just as in Heliozoa, they are covered with small granulations, but 

 are even smaller here; and besides, they have sometimes a peculiar 

 appearance, which does not seem to have been observed in Heliozoa 

 as a rule : as long as they have not attained to their entire develop- 

 ment, their tip is blunt, truncated at a right angle to the longitudinal 

 axis; but when fully extended, they are pointed; one might suppose 

 that in the first case the layer of viscous plasma which covers the 

 axial thread did not extend further than the axial thread itself, 

 and in the second case it had gone farther, lengthening to a point. 

 Axial filaments exist here indeed, as in typical Heliozoa, and in 

 favorable conditions they may be seen to penetrate the plasma and 

 converge towards a central granule, which itself is easily distin- 

 guishable, and with carmine stains quickly. But this "central 

 granule" is in fact never quite central but lies at a greater or less 

 distance from the center toward the anterior extremity. 



This central granule is itself surrounded by the special apparatus 

 which Gruber (14), Blochmann (3), Schouteden (31) have already 

 described in Dimorpha mutans, but which is here of a rather differ- 

 ent nature, consisting of very small, yellow, spherical grains, which 

 are set around the central granule like numerous radiating chap- 

 lets, owing, very likely, to their being attached to the axial fila- 

 ments which converge towards the centre. x\ll together, they build 

 up a kind of spherical cage, quite characteristic of Dimorpha 

 tetramastix and allowing one easily to distinguish this species from 

 any Heliozoon in the vicinity. 



Food is caught by the pseudopodia, and in a very characteristic 

 manner. On four or five different occasions I observed the cap- 

 ture, and always it was the same small Infusorian, Balanitozoon 

 agile, which suddenly came into contact with one or several of the 

 pseudopodia; these then tightened around their captive, and at 

 the same time a very thin film or velum came creeping over the 

 pseudopodia, lengthened into a cup, and finally closed behind the 

 Infusorian. This latter, which had been suddenly killed as by some 

 special poison, became more and more elongated, then was cut into 



