OF THE RHIZOPODA IN GENERAL :—RETICULARIA. 29 



taken-in as food, whilst the introduction of others, that happened to he on the surface of the glass, 

 took place under actual observation. These granules were in a state of continual movement, 

 passing from the interior of the body and along the stem and branches of the pseudopodial 

 expansions towards the extremities of these, and then back again into the interior of the 

 body, in the manner that will be more particularly described in Gromia. The current was 

 rapid, and seemed to attain its maximum of intensity at the surface of the pseudopodia. It 

 was noticed in this interesting animal, which was kept for several days under observation, 

 that the pseudopodia were always most expanded in the absence of light, being splendidly 

 displayed when the slip of glass was first brought out of darkness and placed upon the stage 

 of the microscope ; but that after a few moments they began to retract themselves, their 

 viscid substance flowing rapidly towards the body with a wave-like motion ; and in a short 

 time it became impossible to recognise a Rhizopod in the dark motionless mass beneath the 

 microscope. 



33. In the Gromia, some forms of which inhabit fresh water, whilst others are marine, 

 the sarcode-body, which is of essentially the same character with that of Lieherkiihnia, is 

 enclosed in a yellowish-brown membranous " test " of ovoidal shape, with a single round 

 orifice of moderate size, through which the protoplasmic substance extends itself from the 

 interior through the surrounding medium (PI. Ill, fig. 2). When the animal is in a state of 

 rest, the whole of this is drawn within the test; and when its activity recommences, single 

 fine processes are first put forth, which move about in a sort of groping manner until they 

 find some surface to which they may attach themselves. When this attachment has taken 

 place, new sarcode flows irtto them, so that they speedily increase in size ; and they then 

 elongate themselves by sendit^g out finer ramifying processes, which, in diverging from each 

 other, come into contact with' those proceeding from other stems, and, by mutual fusion, form 

 a set of inosculations or connecting bridges between the different systems of ramifications, so 

 that the whole becomes a complicated network extending to a distance of six or eight times 

 the length of the body. This network continues to undergo incessant changes, new filaments 

 being put forth in diff'erent directions, sometimes from its margin, sometimes from the midst 

 of its ramifications, whilst others are retracted. Not unfrequently it happens that at a spot 

 where two or more filaments meet and fuse together, a lamina is formed by an expansion of 

 the viscous protoplasm that flows towards this point; and from such an expansion a new set 

 of thread-like processes is given off", as from the central body, of which several examples are 

 shown in the figure. It is not only, however, in the protoplasmic substance directly as it 

 issues from the mouth that the pseudopodia originate ; for this substance is seen to 

 extend itself over the surface of the test, and may put forth pseudopodia from any part of it. 

 The greater development of these at the posterior extremity of the shell would seem 

 to indicate that they are employed for fixing it, and thereby cnaljling the animal to put 

 forth more power when seizing and drawing into itself as food living creatures that can 

 struggle against its ensnaring action. (The greater part of the Foraminifera are firmly fixed 

 by the adhesion of their shells to the surfaces of Algse, Zoophytes, Mollusks, &c.) Any minute 

 particle which may chance to come into contact with a pseudopodium, and which is retained 

 in adhesion to its viscid surface, soon becomes imbedded in its protoplasm, and is subjected 

 to the general movement to be presently described. But when a larger body is thus 



