98 PROTOPLASM 



ture is to be observed, although the continual rapid dis- 

 placements of the network render the observation difficult. 

 The thicker pseudopodial stems and the basal rim usually 

 have the structure of a fibrous network similar to the above- 

 described bridges of protoplasm. Naturally this fibrous 

 structure always appears more or less confused, but the meshed 

 structure is usually especially distinct in the webbed mem- 

 branous expansions. These are, as a rule, excessively thin, 

 since they are built up of a single layer of alveoli or meshes, 

 and therefore they also show the structure in the clearest 

 manner (Plate IV. Figs. 1 and 2). Fig. 1 represents such 

 a membrane of a Miliolid in the living condition ; Fig. 2, 

 on the other hand, that of a Discorhina after fixation with 

 vapour of osmic acid and very strong staining with Dela- 

 field's haematoxylin. It is beyond doubt that in both cases 

 the observation yields exactly the same results. Since we 

 are dealing with a protoplasmic layer of excessive thinness, 

 the object is very faintly defined even in an intensely stained 

 preparation, and demands very careful attention and 

 study. In the figures the dark granules, staining intensely 

 with hsematoxylin, may also be noticed distinctly ; they 

 occur in great numbers, as is weU. known, in the pseudo- 

 podial network of these Ehizopods, and display the so-called 

 granular movement. Finally in Fig. 2 the nodal points 

 of the meshwork can also be made out very plainly. 



The reticular structure shows up especially clearly in the 

 lumps of protoplasm, which, like the granules, are carried to 

 and fro on the fine pseudopodial threads. The distinctness 

 of their meshed structure seems to depend principally on 

 the fact that their protoplasm is in a condition of relative 

 quiescence, so that the meshwork undergoes no displace- 

 ments. It is remarkable that such lumps occasionally 

 adhere to the pseudopodia in a state of complete rest, while 

 the moving granules rush past them uninterruptedly. 



The most difficult problem is presented by the fine 

 thread-like pseudopodia, the thickness of which can scarcely 

 be measured even when the highest magnifications are 

 employed, and which may be so attenuated in the peripheral 

 expansions of the pseudopodial network as even then only 



