THE INTIMATE STRUCTURE OF THE CELL 183 



cell of this species has received close attention, especially at 

 the hands of West and Griffiths, and of Virieux. 



The cell wall is well defined, double contoured, and is not 

 composed of cellulose. It is easily separated from the proto- 

 plast by plasmolysis. It measures 2 — 3/x in tliickness and can 

 be made to swell by the use of various reagents. When thus 

 treated the swollen outer layers show, with high magnification, 

 a mass covered with minute granular objects and numerous 

 short filaments. These filaments were at first considered to 





-^,-i 





\^ 



a b 



Fig. 51. 



a. — Achromatium oxaliferuni. Figure given by West and Griffiths as a copy 

 of one of Schewiakoff's figures of Achromatium, in which is shown a 

 marked distinction between peripheral and central cytoplasm. 



6.— Figure oi Achromatium oxaiiferum as given by Virieux in which no such 

 distinction between the peripheral and central positions is shown. 



be short peritrich cilia arranged in the cell somewhat after the 

 manner of the cilia arrangement in the Diatoms. Virieux 

 found, however, that they are an artefact. The cell wall is 

 lamellose, consisting of several firm layers with intervening 

 layers which become gelatinous on the addition of carbolic 

 acid. From its behaviour with certain chemical reagents 

 West and Griffiths concluded that the cell wall is composed of 

 a substance analogous to fungus cellulose. 



The protoplast is uniform and composed of a reticulum 

 evenly distributed throughout the cell. In the work of earlier 



