G50 SUMMARY OF CURRENT RESEARCHES RELATING TO 



valve of the frustule. In an effort to make the diatom roll over, so 

 as to make more sure of its species, it was swept out of sight and 

 lost. 



A little later some fresh samples of similar material afforded a 

 repetition of the phenomena, and confirmation of the facts. A 

 frustule of the same species as the former was so wedged in the 

 compressor that one end was free, while the other was fast. The 

 free end would move vigorously one way or the other, in an arc of a 

 circle, but the diatom was not released. Attached to it were two 

 gelatinous masses, one on each side, and of similar size to those 

 described in the former case. These were distinctly applied to the 

 valves so that, as the diatom lay in front view, as before, the two 

 masses were on the opposite side of the frustule. These masses 

 moved along the sides, sometimes the whole length of the diatom, 

 sometimes only to the middle, where they would rest awhile, and 

 then either complete the motion or go back. They did not always 

 move simultaneously, nor with the same speed, but with a general 

 agreement of motion. This action was continued half an hour, the 

 diatom not getting free. 



Turning to another part of the slide, another free-moving speci- 

 men was foimd with a similar gelatinous mass in contact with it. 

 The diatom was moving freely and towing the matter along with it, 

 attached to its hinder end. Soon the mass began to move forward on 

 the shell, the motion of the diatom ceased and was presently reversed, 

 the order of sequence being distinctly as stated. In several instances 

 the motion of the gelatinous mass from the rear end of the diatom 

 forward, plainly preceded the change in the direction of the frustule, 

 as if the change of ciliary motion (assuming that to be the motive 

 power, for the sake of illustration) did not instantly stop the headway 

 of the diatom, but required an appreciable moment of time to over- 

 come the momentum. The observation of this shell continued for a 

 full hour, the changes of direction being frequent, and all the acci- 

 dental modifications and phases of the phenomena were strikingly 

 confirmatory of the existence of some force applied along the line of 

 the raphe, acting sometimes in one direction and sometimes in 

 another, in such a way as would be fully explained by supposing 

 ciliary action along that line, but which do not seem to be so easily 

 accounted for by osmotic action, certainly not by osmotic action at 

 the ends of the frustule. 



On one or two occasions the acting force did not appear to be 

 reversed at the same instant at the two ends of the diatom. Twice 

 the foreign matter moved against the current of general motion, 

 slowly, it is true, but really in such a way as to indicate that the force 

 acting upon it was not in the same line of direction as was that 

 exerted on the other half of the frustule. But when the motion 

 controlling the gelatinous mass became vigorous, it either was domi- 

 nant or was indicative of harmonious action at both ends of the 

 shell, so that the motion of the diatom through the water became very 

 pronoimced and strong. 



Mr. Cox looked for similar phenomena among the other kinds of 



