28 OF THE RHIZOPODA IN GENERAL :— RETICULARIA. 



freed from adhering particles, its membranous base is thin, transparent, and colourless ; 

 sometimes it extends into spine-like processes, by which the test adheres to a fixed point 

 of attachment. The animal of BiJJlugia appears closely to resemble that of Arcella, but has 

 not been so carefully studied. 



Order RETICULARIA. 



32. As each of the preceding Orders contains both naked and testaceous forms, so 

 do we find that with the proper Foraminifera furnished with calcareous shells, there must 

 be associated (in virtue of the close conformitj^ in the nature and actions of their 

 sarcode-bodies) animals which only form a membranous " test," and some even which seem as 

 destitute of any protective envelope as an Amaba or an Aciinophrys* An example of this last 

 kind, which afi'ords an admirable illustration of the essential features that distinguish this 

 group (^ 11), is presented by the Lieberhihnia, a very remarkable Rhizopod, which has been 

 found in the neighbourhood of Berlin, by MM. Claparede, Lachmann, and Lieberkiikn 

 (xxv, pp. 464-466). t The body of this animal (PI. II), which measured about l-16th millim. 

 (l-400th inch) in its longest diameter, was formed of a mass of granular protoplasm not pre- 

 senting any distinct differentiation of "endosarc" and "ectosarc," and destitute alike of 

 "nucleus" and "contractile vesicle," but including a large number of "vacuoles" filled with a 

 homogeneous liquid. From one portion of this mass there issued a sort of stem, from which 

 all the pseudopodia diverged ; and this stem was enveloped in a transparent sheath, which 

 might be traced, as a thin pellicle, over the whole surface of the body. From this stem the 

 granular protoplasm extended itself into branches, whicii ramified with extreme minuteness 

 and to an extraordinary distance, their length in proportion to the diameter of the body 

 being nearly three times that which is represented in the plate. Wherever these ramifying 

 pseudopodia came into contact with each other, the substance underwent a complete fusion 

 or coalescence ; and thus a network was formed, which might be described as a sort of 

 animated spider's web, and which was admirably fitted for the acquisition of food. Any 

 small particles that come into contact with these pseudopodia were held to their surface by 

 adhesion, and then partook of the general movement of the granules included in the proto- 

 plasm to be presently described. But when larger bodies were thus entrapped, they became 

 enclosed in a sort of sheath of protoplasm formed by the blending of the neighbouring 

 pseudopodia whicli applied themselves to its surface ; and by the progressive contraction of 

 this they were drawn towards the body, as in the Adinoplinjs (1 14). In one instance a large 

 Stentor thus captured was seen to make its escape, carrying with it a portion of the pseudo- 

 podial expansion of the Lieherhiihiia. The granules so abundantly distributed through the pro- 

 toplasm of the body and its extensions were obviously for the most part of external origin ; 

 many of them being particles of chlorophyll derived from vegetable organisms that had been 



* On this group see especially iv, xxv, x.xxiii, xxxv, xxxvr, lxxxiv, xcvii. 



t The animal described by Professor Bailey (iv) under the name of Pamphagus mulabilis seems to 

 have been nearly allied to this, if not identical with it. 



