90 SALIVARY CORPUSCLES. 



the tissues of the web itself." But even if we were to 

 assume the existence of such a system of nerve cells 

 and fibres, we should be unable to account for the 

 change unless Mr. Lister or some one else could ex- 

 plain how such an apparatus would cause little par- 

 ticles to move to and fro in fluid contained in the 

 interior of a cell ; but we should have to add 

 hypothesis to hypothesis before we should arrive at a 

 plausible solution of the fact, while, on the other 

 hand, a much simpler explanation is afforded without 

 supposing direct nervous action at all. The currents 

 setting towards the mass of bioplasm in the centre of 

 the cell, and the varying quantity of fluid diffusing 

 through the tissues under varying degrees of vascular 

 distension, which we know actually do occur, fully 

 account for the phenomenon. These pigment par- 

 ticles which we see actually moving prove to us the 

 existence of currents of fluid through tissues to and 

 from the masses of bioplasm. "We may be sure that 

 similar changes occur in other tissues, and that in 

 the perfectly transparent anastomosing stellate cells 

 of the cornea, for example, corresponding alterations 

 are continually occurring during life. 



132. Salivary Corpuscles. Another striking ex- 

 ample of movement resulting from changes in the 

 bioplasm or living matter is seen in the rapid move- 

 ment of little particles in the fluid or semi-fluid 

 material of which the salivary corpuscle is in great 

 part composed. Owing to the constant disturbance 

 of the fluid caused by the currents flowing to and 

 from the actively growing living matter, the little 

 particles suspended are kept in a state of constant 

 agitation, now forced towards the surface, and then 

 as rapidly whirled towards the centre, perhaps sud- 

 denly stopped and driven again in an opposite direc- 

 tion. These movements are very remarkable. The 

 actively moving particles in the interior of the cor- 

 puscle can be seen with a good quarter of an inch 



