OF CILIATED CELLS. 87 



and is generally influenced by any alteration in ex- 

 ternal circumstances which exert an effect, favour- 

 able or unfavourable, upon bioplasm. The proportion 

 of bioplasm or living matter in ciliated cells is con- 

 siderable, and its relation to the cilia is such as to 

 favour the view that it is intimately concerned in the 

 movements. Nutrient matter is taken up by the 

 mass of bioplasm upon the side opposite to that nearest 

 to the cilia, and it seems probable that the production 

 of formed material, and a consequent alteration in the 

 tension of the texture of which the cilium is com- 

 posed, accompanies each movement. I think that the 

 rate of vibration enables us to measure the rapidity 

 of nutrition, and that the to-and-fro movement marks 

 the change of pabulum into bioplasm, and the latter 

 into formed material. This change, which in many 

 cases is probably continuous, here gives rise to an in- 

 terrupted movement, perhaps because the elastic 

 porous tissue of the cilium suddenly expresses from 

 its meshes the fluid which had just previously passed 

 into them from the bioplasm. 



An objection has been raised to the view I have 

 advanced, on the ground that the part of a cilium. 

 of ciliated epithelium which dies first is the base, or 

 that part which is nearest to the living bioplasm, not 

 the apex which is most distant and which is un- 

 doubtedly the oldest part of the cilium and that 

 which was first formed. This argument which has 

 been advanced by Prof. Rutherford, would have been 

 regarded by me as of great importance if it had 

 been proved that the cilium itself was bioplasm or 

 living matter. But so far from this being the case, it 

 is almost certain that the cilium is composed of lifeless 

 passive formed material, the movements of which 

 are caused by the changes effected by the living 

 bioplasm at its base. Now, it is obvious that an 

 impulse forcible enough to produce even considerable 

 movement of the thin free extremity of a cilium 



