THE ACTIVE FORCES OF LIVING ORGANISMS 31 



you leave a brain for some weeks in strong alcohol, it 

 becomes, as is very well known, hard and compact. 

 The meaning of this is doubtless that a general con- 

 traction of the molecules, of which its substance is 

 composed, has taken place; they have, that is to 

 say, grouped themselves in closer order. The results 

 thus obtained indicate to some extent the physiological 

 action of the various substances mentioned on the 

 nerve-cells in a living animal. If we adopt the 

 modern view that ether permeates all matter, it is 

 evident that the molecules of nerve-cells must be sur- 

 rounded by it. When, therefore, they vibrate, as in 

 nervous action they probably do, there is, as it were, 

 a link between them and the molecules of any foreign 

 substance — such, for instance, as strychnine in the 

 blood — and the movements of the nervous molecules 

 would, under these circumstances, naturally tend to 

 become influenced and modified by their surround- 

 ings ; and this, it may be supposed, would occur 

 whether or not the strychnine molecules were taking 

 part in the chemical action going on in the blood or 

 lymph around the nerve-cells. 



If we suppose that the molecules of nerve - cells The 

 vibrate in agreement with the degree of oxidation physio- 

 and the degree of contraction of the tissues to which relSion. 

 they correspond, it is evident that any change in the 

 latter must be followed, or accompanied by, a modifi- 

 cation of the vibrations of the former ; therefore, 

 when the system is stimulated to increased oxidation 

 these vibrations must be affected thereby. But as the 



