30 OF THE lllIIZOPODA IN GENERAL :—RETICULARIA. 



entrapped, a number of pseudopodia apply themselves to its surface, and a sort of flux of 

 their viscid protoplasm takes place towards it, until it becomes ensheathed with this 

 substance, as shown in the case of the Diatom entangled amongst the pseudopodia on the 

 right side of the figure. A reflux of the protoplasm of the pseudopodia then takes place, and 

 the body entrapped by them is gradually received into the mass of sarcode lying outside the 

 mouth of the test, through which it passes into its interior if not too large to find 

 admission. The lorica of Diatoms, portions of Confervm, and other similar bodies, bearing a 

 considerable proportion in length to the whole diameter of the test, may often be distin- 

 guished in its interior, as shown in fig. 2. — As the form of the test of Gromia does not 

 admit of any addition being made to its capacity, so as to accommodate it to the growth of 

 the contained body, it appears probable that the latter (like Arcella, "f 31) quits it, and forms 

 a new test whenever it has outgrown the old one ; and it does not seem unlikely that an 

 accumulation of indigestible substances may be got rid of at the same time, as the enclosure 

 of the body in a firm envelope must prevent these from being ejected from time to time 

 through an extemporised anus, with the facility which we have seen to characterise the 

 process of defecation in the naked Rhizopods. 



34. Through tlie whole of tlie protoplasmic network, a movement of granules is con- 

 tinually taking place, chiefly in two directions — from the bod)' towards the extremities of the 

 pseudopodia, and from these extremities back to the body again. This movement may be 

 seen in every one of the processes ; but it is only in the broader filaments containing 

 numerous granules, that two streams can be seen passing at the same time in opposite 

 directions. In the finest filaments, whose diameter is less than that of the granules, the 

 latter glide along their surface at distant intervals, each passing up as far as the termination 

 of the filament, and then returning, sometimes meeting and carrying back with it a granule 

 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 difi'erent 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. This curious circulation, as already pointed out (f 11), so nearly resembles the 

 cyclosis that takes place within the cells of PJant.s, as to leave no reasonable doubt that the 

 conditions of the two sets of phenomena are essentially the same. 



35. In one large section of the Foraminifera, of which Miliola may be taken as the type, 

 the calcareous "shell," whether monothalamous or polythalamous, is formed upon the same 

 plan as the "test" of Gromia ;* the wall of each chamber being perforated by no other openings 



* Althougli the author lias here followed the example of other Systematists in separating Gromia 

 and its naked allies from the true Foraminifera, he is by no means certain that such separation, h(?wever 

 convenient in practice, is scientifically justifiable ; since the difference in the coinpositiou between the 

 membranous "test" of Gromia and the calcareous "shell" of Miliola scarcely seems to him a character 



