ON THE STRUCTURE OF OSCILLATORI.E. 253 



nislied, since the question arises, is the spinnings round of the 

 thread the prirrmm mobile, the agency by which the motion of 

 the filament is effected, or is the motion of the latter due to 

 another cause, say for instance, ciliary action, in which latter 

 case the apparent motion of the axis or thread might be 

 accounted for by the revolving of the filament, which not 

 being distinctly observable would have the same effect as if 

 the thread alone spun round in propelling the fil-'iment. Still 

 after the most careful and patient observation, I must retain 

 my original opinion, viz., of the thread possessing independent 

 motion, and being the cause of the motion of the filament, for 

 the following reasons. I purposely watched and repeatedly 

 observed, while only the most gentle oscillations were observ- 

 able in the filament, the thread which was very distinct in 

 two adjoining cells, vanish out of one and not out of the other. 

 The gentle tremor of the filament could hardly be due to a 

 revolving of the filament ; but even supposing it did revolve 

 at the time, as the thread in both cells was equally prominent ; 

 if its disappearance in one cell was owing to the revolving of 

 the filament, it ought also to have disappeared in the other cell 

 for the same reason. Similar appearances I have observed in 

 filaments which were partly bent, approaching the figure S, 

 and which could not have revolved around their axis without 

 its being plainly seen ; yet, as in the former instance, the 

 thread could be seen altering its position in the different cells. 

 As a further reason for retaining my original opinion, I will 

 mention that by careful observation the body of the filament 

 itself may sometimes be seen to bend simultaneously while 

 the thread is seen to retract in the manner described above. 

 And, lastly, though using all the best means which have been 

 recommended by experienced observers, for the detection of 

 cilia, I have been unable to discover any ; and I would caution 

 other observers, in looking for them, not to mistake certain 

 appearances presented by the filaments under oblique light 

 and an object-glass of great angular aperture, which closely 

 resemble a fringe of cilia, though they are simply the result 

 of the highly refractive property of the filaments. 



I have been thus particular in stating what I have seen, as 

 I am most anxious that other observers, with superior means 

 of investigation, whom I hope to induce to verify or correct 

 my own observations, should exactly know what I had seen ; 

 and as I have provided myself with a good stock of this 

 interesting species, I shall be very happy to forward some of 

 it to those who feel interested, and inclined to investigate for 

 themselves what I consider to be a most important point in 

 vegetable physiology, viz., the various motions observable in 



