8 Transactions of the Societij. 



due to the fact that it is made in a cup into which material slowly 

 trickles at the edge. The greater portion of such material, when 

 the pellet has reached a certain size, would be whirled on to it 

 before reaching the bottom of the cup — and the nearer any 

 portion of the pellet was to the bottom, the less its chance of 

 getting fresh accretions. Hence, in the main, arises its subconical 

 shape. Such a shape would be readily thrown by the motions of 

 Melicerta out of its first position, in which its longer axis is at 

 right angles to the lower portion of the cup, into a new position in 

 which that axis lies across the cup ; and once in this position it 

 would not be very easy to get out of it. The action of the cilia on 

 it in this new position would now obviously tend to make it rotate 

 round its longer axis, as those cilia opposite to the extremities of 

 that axis would have their action checked by the pellet itself. 

 Moreover, the fresh material would noiv tend to be mainly arranged 

 round the pointed end, as it would be only those cilia which were on 

 either side of it that would have perfectly free action ; those oppo- 

 site the larger end being constantly checked by the pellet's touching 

 them. This would finally lead to a roughly cylindrical pellet of 

 the usual form. 



But I am afraid that I have already j)ursued the subject too far 

 for the reader's patience ; I will only say, in conclusion, that I 

 heartily sympathize with IMr. Bed well's appreciation of the wonders 

 of this living atom. Whatever may be the correct explanation of 

 the facts he so lucidly describes (and I am by no means confident 

 that my own is the correct one), the facts themselves remain a per- 

 petual source of wonder and delight to all who, like himself, not 

 only possess a Microscope, but are able to use it. 



