112 PALMER : 



■more or less deeply overlaid 7vith coleoderm substance of varying 

 consistency ^ and itself asstiming that degree of fluidity ivhich 

 best meets the reqtdrem,ents of the situation, permeates the raphes, 

 circ7ilates in the keels, or in some cases protrudes quite beyond the 

 silica, and functions as the actual propidsive agent. 



This statement of the matter, though perhaps somewhat 

 general in form, is not the result of mere cogitation. It is 

 the carefully pondered outcome of several years' stud}' of the 

 phenomena of diatom motion, a studj^ that has not seemed to 

 me to be altogether superficial in character. I know of no 

 fact inconsistent with this concept, and in this I include the 

 actual facts brought to light by L,auterborn himself. It is 

 encouraging to find, also, that the statement expresses approx- 

 imately the views ef Max Schultze. 



The elucidation of the details of mechanism, as these pre- 

 sent themselves in the many types of the Bacillariacea; , would 

 prove in the end an uncompleted task of a long lifetime. 



