Cytology and Movements of the Cyanophycece. 323 



Fischer (28) found membranous projections passing 

 from around the central body into the surrounding chroma- 

 tophore. He considered them to be continuous with the 

 protoplasmic membrane around the chromatophore (Figs. 

 29 and T)2 are copies of his drawings). These membranous 

 projections, I think, are evidently the prolongations of the 

 ground mass from the central body or nucleus, to the cilia, 

 though he failed to see them pass the cell wall (compare 

 Figs. 29 and 32 with Figs. 31 and 38). I have, with 

 Engelmann, been able to see Oscillaria and Cylindrosper- 

 niiim swimming freely in the water, which is beyond the 

 power of pseudopodia to cause. It is therefore evident that 

 the creeping movements of these organisms are effected by 

 the action of definite, very delicate, short cilia. These were 

 demonstrated around the wall of the cells in a more or less 

 uniform number (compare the various figures). 



The contention of former writers that motion in the 

 Cyanophyceje was caused by light, heat, etc., does not in any 

 way militate against the views here taken. The effects of 

 these stimuli are but the workings of the ordinary laws of 

 biology. Wigand (84) showed that light was a prime fac- 

 tor in the protoplasmic movements of the higher plants, and 

 in the Cyanophyceae we find the same thing to be true. 

 Movement is much stronger in the light than in darkness, 

 and it is probable that if they could be observed in total 

 darkness, there would be no motion at all. The action of 

 heat and cold was also the same in these organisms as in the 

 higher cells. By means of Reichert's warm stage, I observed 

 these organisms under varying conditions of temperature 

 and found that they had their maximum, optimum and 

 minimum temperatures, just as found in other plant cells. 



(8) Conclusions. 



The line of demarcation between the Cyanophycese and 

 the other algae has been based upon the threefold negative 



