238 H&CKEUS VIEWS. 



action advocated by me, and if the cilium itself were com- 

 posed of living matter, like the body of an amoeba, such 

 an objection would undoubtedly hold : but if, on the other 

 hand, the movement is physical, due to alterations in the 

 currents of fluid through the cell, we should expect that it 

 would continue longer at the apex than at the base, for the 

 simple reason that an impulse which would be sufficient to 

 make the thin free part vibrate freely might be insufficient 

 to move the thicker portion attached to the cell. We 

 cannot, I think, say that the cilium dies from base to apex, 

 for the whole vibratile appendage is probably as destitute of 

 life while it is yet vibrating actively, as after it has ceased to 

 move. If we could only make fluid flow through the cell after 

 its death uninterruptedly in the same direction, and with the same 

 force as it is made to flow during life by the action of the 

 living matter, ciliary movement would, I think, continue, 

 although the living matter of the cell was actually dead. It is 

 most important to distinguish between vital movements 

 occurring in matter which is actually alive, and mechanical 

 movements which result from alterations in tension, the flow 

 of currents, &c., consequent upon changes effected by living 

 matter. 



Haeckel, however, believes that ciliary movement is 

 dependent upon the same causes as the movement of the 

 amoeba and other forms of living matter ; and his view is 

 no doubt correct as regards the long hair-like appendage in 

 some of the monera, for Haeckel has seen this vibratile 

 process undergo change and become an " amoeboid 

 process ; " but the statement is certainly not applicable to 

 all cases. Neither the tail of the spermatozoon, nor the 

 cilia of the epithelium of the mouth of the frog and toad 



