OSCILLARIA. 309 



in the cell contents. The creeping movements, he holds, can 

 not be due to protrusions of the internal protoplasm, since each 

 filament is enveloped in a gelatinous sheath, which is not com- 

 posed of protoplasm. The cells also exhibit motion when the 

 envelope itself is at rest. The movements must originate in 

 the protoplasmic contents of the cells themselves and are prob- 

 ably of the same nature as those of the sarcode in the so-called 

 pseudo-podia of rhizopods and other protozoa." 



Life, whether vegetable or animal, is a mystery to the philo- 

 sophic niind ; to attempt a detailed explanation of cause and 

 effect would be presumptuous, but a remark or two may not be 

 out of place. By the careful observation of living plants the 

 process of cell-multiplication can be readily detected in the 

 larger forms. Ordinarily the split of a cell commences on one 

 side and then continues from the opposite side ; a number of 

 cells dividing at the same time will have the tendency to throw 

 the end of filament (Kit of line, first on one side and then on the 

 other, thus producing the. vibratile motion. The process of 

 creeping may be conceived in connection with growth, and yet 

 it may not satisfactorily explain every movement. The appar- 

 ent correspondence between the rapidity of growth, and that of 

 the creeping filaments is not without significance. Larger forms 

 of Oscillaria are found to grow by cultivation at the rate of 

 about one-half inch in an hour. The creeping of the same fila- 

 ments progresses at the same rate, age of the filaments and other 

 circumstances corresponding, hence the reasonable inference of 

 relation between the two movements. 



A. Articulation of filaments often indistinct. 



OSCILLARIA SUBTILISSIMA, Kg. 



Filaments often solitary, but also forming a yellowish 

 green stratum, sometimes convolute ; cell contents light 

 yellow-green. 



Diameter of threads, 1-1.5 p.. 



Not infrequent on wet, marsh grounds. 

 Plate CCVI, fig. 1. 



OSCILLABIA TENERRIMA, Kg. 



Filaments thicker than the preceding; ends somewhat 

 attenuated and bent ; cell contents light aeruginous or with 

 tendency to olive. 



Diameter, 1.8-2. 5 jw. 



In ditches, among decayed vegetable matter. 

 Plate CCYI, fig. 2. 



