SINGULAR MOVEMENTS. 161 



one of its surfaces. And these and similar pheno- 

 mena occur simultaneously with several remote and 

 independent particles of matter. 



These phenomena (for the details of which I must 

 refer my readers to Dr Wallich's own admirable 

 memoir*) are quite inexplicable on the hypothesis of 

 exosmotic and endosmotic action, to which the motions 

 of the Diatomacece had been referred by the best pre- 

 vious authorities. To explain them consistently, we 

 are irresistibly led to infer the existence of numerous 

 long prehensile filaments ; capable of protrusion, of 

 extension and retraction ; of extreme tenuity, yet of 

 extraordinary strength and elasticity; in virtue of 

 which both the ordinary to-and-fro movements, and 

 the secondary motions affecting surrounding bodies, 

 are performed. It is true, no trace of such filaments 

 can be detected with the highest powers of magnifica- 

 tion yet brought to bear on them ; but the inference 

 of their existence from the phenomena recorded seems 

 unavoidable, or, in other words, the phenomena are 

 inexplicable on any other hypothesis. 



To me it appears that the whole of these observa- 

 tions, though they do not settle the point of the sys- 

 tematic rank and position of these organisms, do add 

 a considerable weight to the opinions of those natural- 

 ists who refer the Diatomacece to the animal rather 

 than the vegetable kingdom ; the presumed retractile 

 and extensile processes bearing a very distinct analogy 



* Annals and Magazine of Natural History for January, 1860, 

 p. 15, ct scq. 



