108 SUMMARY OF CURRENT RESEARCHES RELATING TO 



or exosmose takes place. At the anterior end, where the micrococci 

 always vibrate more feebly, there ensues the opposite phenomenon — 

 absorption of the water or endosmose, which does not act on the 

 suiTOunding parts with such force as the discharge of water does at 

 the posterior end. 



(3) As already remarked, the vibrating force of the micrococci is 

 distributed uniformly round the cell, when the alga naturally assumes 

 a quiescent state, which always happens after a backward or forward 

 movement. But it sometimes occurs that the moving cell touches 

 some foreign body with its side, and thereby is stopped in its motion, 

 or its anterior end strikes against an insurmountable obstacle. A 

 pause thus artificially produced is not accompanied by any uniform 

 distribution of the vibrating micrococci, but on the contrary, the latter 

 continue to maintain the distribution which they had during the 

 motion, i. e. at the posterior end is seen the most intense and most 

 widely extending vibration, while at the anterior end it is neither so 

 violent nor so noticeable. In the first case the osmotic phenomena 

 evidently occur with equal force at both ends, as the result of which a 

 pause naturally ensues ; but in the second case the osmotic phenomena 

 continue to be so distributed that the endosmose is concentrated in 

 front and the exosmose behind. The cause of the motion does not 

 in this case pass away, it is simply paralyzed by an entirely accidental 

 external impediment. 



(4) An entirely analogous distribution of the vibrating micrococci 

 also occurs when the diatoms rotate laterally, as mentioned above. In 

 this case the difference is that the strongest vibrations are now noticed 

 on one side of the alga (Fig. 3), on the side from which the rotation 

 proceeds ; on the side, however, towards which the motion is directed, 

 the micrococci vibrate much more feebly. Besides this it should be 

 mentioned that the vibration is not evenly distributed on the whole 

 side, but is localized at the free end only (i. e. the free movable end 

 which is not attached to the slide). 



(5) That the peculiar way in which the micrococci move is 

 not the result of the motion of the alga itself, and of the current 

 produced thereby in the water, is proved by the fact that the gentlest 

 and slightest movements of the alga, which are incapable of producing 

 in any way such considerable currents, nevertheless bring about the 

 distribution of the micrococci described above, with all their peculi- 

 arities which become apparent with stronger movements. 



(6) If it were still thought that the strong osmose, the existence 

 of which is now placed beyond doubt, may be only an attendant 

 phenomenon and not the actual cause of the movements observed, 

 such an idea would be refuted by the following fact. It was possible 

 generally, by great attention, to determine beforehand in what direction 

 the movement would take place. A little time (a fraction of a second) 

 before the movement occurred a specially increased vibration of the 

 micrococci could generally be noticed at one end of the alga, and as 

 the result of the observations already described, it is not difficult to 

 foresee that this end is destined to be the posterior, the other the 

 anterior end. This fact, which I had an opportunity of proving 



