THE ACTIVE FORCES OF LIVING ORGANISMS 43 



general interest that it may be worth while to con- 

 sider certain other aspects of it. The power of 

 attracting and repelling is, as everyone is aware, one 

 of the primordial properties of matter, and is fre- 

 quently brought into play by the variations of chemical 

 environment which in any given case may happen to 

 obtain. Since in animal tissues oxidation and de- 

 oxidation are the common basis of all movement, the 

 vibrations of nerve-cells may without doubt be attri- 

 buted to the same general cause, and if this be so, 

 then variations in the mode of vibration must evidently 

 depend on the degree of oxidation. Bufr it is cer- 

 tainly very difficult to imagine any variations of 

 movement and of position amongst the molecules of 

 nerve-cells which would better correspond to changes 

 in the degree of oxidation than would variations of con- 

 traction and expansion. If the nerve-cell itself were 

 contracted, or if within it the molecules were grouped 

 more closely together — it may be in tiny collections 

 such as would give it the granular appearance we 

 know it to possess — the molecules would, one might 

 suppose, react on one another with greater rapidity, 

 and if the grouping were not too close, with greater 

 intensity. Such a grouping would correspond to a 

 state of diminished oxidation, for many of those drugs 

 which produce a diminution of oxidation cause con- 

 striction or drawing together of the tissues with which 

 they come in contact, and within certain limits an 

 increase in the intensity of nervous vibration. The 

 nature of glandular secretion during very violent 



