Cytology and Movements of the Cyanopkycece. 313 



demonstrate the position of the flagella described by him. 

 The probabiHty is that he referred to the long hair-Hke 

 projections from the end cells, which have been described 

 by Borzi and Hansgirg as parasitic organisms, and to which 

 he here gave the functions of definite plant organs. He also 

 intimated that pseudopodia about 0.03 mm. in length 

 passed through the cell wall. The only figure in all of the 

 literature reviewed which shows any such organs, other than 

 these so-called parasitic growths, accompanies Zukal's paper 

 (loi) where he figures several long whip-like flagella 

 springing from the division walls of C ylindrospermum stag- 

 nate, though no mention of them is made in the paper. ( See 

 Fig. 65, which is copied from Zukal's drawing.) 



Hogg (42) found cilia on the ends of diatoms and in 

 isolated positions along the sides, but his views have received 

 no support from other investigators, and it is likely that he 

 misinterpreted effects of lighting, as was pointed out by 

 Wenham (82), who considered motion to be due to a pro- 

 toplasmic layer surrounding the frustule. 



Wolle's views (87) were expressed by him as follows: 

 "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 the filament out of line, first on one side 

 and then on the other, thus producing a vibratile motion. 

 The process of creeping may be conceived in connection 

 with growth, and yet it may not satisfactorily explain every 

 movement. The apparent correspondence between the 

 rapidity of growth and that of the creeping filaments is not 

 without significance. The 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 filaments pro- 

 gresses at the same rate, age of the filaments and other 

 circumstances corresponding; hence the reasonable infer- 



