RHIZOPODA RETICULARIA. 437 



326. Reticulata. — The peculiarities of this type have been 

 most fully studied in a remarkable naked form, which has been 

 described by MM. Claparede and Lachmanu* under the name 

 of Lieberkiihnia. The whole substance of the body of this 

 animal and its pseudopodial extensions is composed of a homo- 

 geneous, semifluid, granular Protoplasm ; the particles of which, 

 when the animal is in a state of activity, are continually per- 

 forming a circulatory movement, which may be likened to the 

 rotation of the particles in the protoplasmic network within 

 the cell of a Tradescantia (§ 289). The entire absence of any- 

 thing like a membranous envelope is evinced by the readiness 

 with which the Pseudopodian extensions coalesce whenever they 

 come into contact, and with which the principal branches sub- 

 divide into finer and yet finer threads, by whose continual inos- 

 culations a complicated network is produced. Any small alimen- 

 tary particles that may come into contact with the glutinous 

 surface' of the pseudopodia, are retained in adhesion by it, and 

 speedily partake of the general movement going on in their sub- 

 stance. This movement takes place in two principal directions ; 

 from the body towards the extremities of the pseudopodia, and 

 from these extremities back to the body again. In the larger 

 branches a double current may be seen, two streams passing at the 

 same time in opposite directions ; but in the finest filaments the 

 current is single, and a granule may be seen to move in one of 

 them to its very extremity, and then to return, perhaps meeting 

 and carrying back with it a granule that was seen advancing in 

 the opposite direction. Even in the broader processes, granules 

 are sometimes observed to come to a stand, to oscillate for a 

 time, and then to take a retrograde course, as if they had been 

 entangled in the opposing current, — just as is often to be seen 

 in Ckara. When a granule arrives at a point where a filament 

 bifurcates, it is often arrested for a time until drawn into one or 

 the other current ; and when carried across one of the bridge 

 like connections into a different band, it not unfrequently meets a 

 current proceeding in the opposite direction, and is thus carried 

 back to the body without having proceeded very far from it. 

 The pseudopodial network along which this ' cyclosis ' takes place 

 is continually undergoing changes in its own arrangement ; new 

 filaments being put forth in different directions, sometimes from 



derived from personal observation. So much remains to be learned, 

 however, in regard to the Life-history of the Rhizopods, and especially 

 as to their Sexual Generation, that the Author does not think it worth 

 while yet to abandon his own classification, which he looks upon as 

 purely 'provisional, for another system which may prove to be equally 

 destitute of the characters of permanence. 



* Etudes sur les Infusoires et les Rhizopodes." Geneva, 1858-1861. 

 The beautiful figure of Lieberkiihnia, given by M. Claparede, has been 

 reproduced by the Author in Plate 1 of his " Introduction to the Study 

 of the Foraminifera." 



