302 PROF. ALLMAN ON THE KECENT EESEAECHES 



rigid as in Clathrulina, it is soft, thin, and flexible, and at the 

 perforation is continued as a very short tubular prolongation 

 round the pseudopodia. The round protoplasm-body does not fill 

 the cavity of the shell, but swings in it free as if hung on the pseu- 

 dopodia which perforate the shell-walls. It contains an oval 

 nucleus with nucleolus ; and close to its margin are situated one 

 or more actively pulsating vacuoles. 



Beproduction by division of the body into two segments was 

 observed with great distinctness. 



Only a single species, H. pellucida, has as yet been discovered. 

 It is found attached by its stalk to the filaments of Algse and 

 other foreign bodies. 



To the Heliozoa rather than to any other group must probably 

 be referred another interesting form which bas been assigned by 

 Cienkowski to a new genus*. He gives it the name of Micro- 

 cometes paludosa (fig. 18). He found it in Russia among gelati- 

 nous algae. The protoplasm-body lies free in the interior of a loose 

 membranous capsule, whose wall, perforated in a few places, affords 

 passage to the very long pseudopodia. The histological differen- 

 tiation of its body is that of most Heliozoa, having a nucleus with a 

 nucleolus, while two or three contractile vesicles exist in the peri- 

 pheral layer. The pseudopodia, which are thrust out through the 

 perforations in the shell, are but little branched, and are sometimes 

 extended to a great length, in order to reach the food at a distance. 

 The end of the pseudopodium may then be seen to flow round 

 the nutritive particle such as an alga-spore, which, when thus 

 captured, will move along the path of the protoplasm filament 

 until it reaches the interior through one of the openings in the 

 shell. During this transport the pseudopodial .filament lies im- 

 movable, while new nutriment-particles move along it into the 

 capsule. 



Besides the reception of food being thus effected by the pseudo- 

 podium enveloping the nutritious particle, the Microcometes has 

 also the power of perforating alga-cells with the extremity of a 

 pseudopodium, and then sucking out their contents in the man- 

 ner of a Vampyrella. 



Multiplication takes place by the division of the protoplasm- 

 body into two parts, which are pressed out through the narrow 

 apertures in the capsule. In the development-cycle there has also 

 been obseryed a resting-state, in which, without leaving its capsule, 



* Arch. f. rnicr. Anat. vol. xiii. 



