MORPHOLOGY AND TAXONOMY OF THE SARCODINA 457 



ment. In Chlamydophrys they form a network as in Allogromia 

 (Fig. 189). 



The tests are simple, one-chambered structures of widely-varied 

 form, frequently ornamented with spines and processes. The basis 

 of all shells is a pseudochitinous membrane which, in some forms, 

 is greatly thickened and constitutes the test; in other cases foreign 

 particles are cemented to the outside of the chitinous membrane 

 (Difflugia, Centropyxis, etc.), and in still other cases silicious plates 

 are precipitated in the endoplasm in the vicinity of the nucleus, and 

 deposited on the chitinous membrane in definite patterns charac- 

 teristic of different genera (Euglypha, Quadrula). 



Reproduction occurs by longitudinal binary division in forms with 

 a soft chitinous membrane, where membranes divide with the soft 



*i 



i 





/ 





/ \ \ \\ 



-■■ 



Fig. 188. — A, Hyalosphenia? sp. (Original.) B, Pseudochlamys patella after Clap. 



and Lachm. 



body (Cochliopodium); in other cases it occurs by so-called " budding 

 division," whereby the protoplasm swells out of the shell mouth to 

 form a bud which assumes the size and shape of the parent (p. 214). 

 Multiple division also occurs in some types; many nuclei are formed 

 by division; these become the nuclei of small naked amebae which 

 after a short period of free movement and growth secrete the shell 

 characteristic of the species. Fertilization processes have been 

 described for several types (Centropyxis, Arcella, Trichosphaerium, 

 Difflugia, etc., Fig. 190), the gametes being either amebulse or 

 flagelluhe. A typical alternation of generations comparable with 

 that of the Foraminifera was described by Schaudinn for the peculiar 

 genus Trichosphaerium. Here asexual processes occur by irregular 

 plasmic divisions (plasmotomy) and by multiple division resulting 



