4 THE ACTIVE FORCES OF LIVING ORGANISMS 



in fact, from the rest of the ether only in the modes of 

 motion to which they are subjected. Such whirling 

 portions possess rigidity through the very fact of 

 their motion,* so that we may say with truth that 

 force, which is merely another name for the motion of 

 matter, is the very essence of matter. It is the cause 

 and origin of all material substances. 



This idea has been rendered more easily compre- 

 hensible by the observation of vortex rings. These 

 are produced by giving at a certain moment to every 

 atom in a plane disc of a fluid a velocity which should 

 be graduated according to its distance from the edge 

 of the disc.t If you take a box, over one side of 

 which a piece of stuff is tightly stretched, whilst in 

 the opposite side a circular hole is cut, and, after 

 filling the box with smoke or other visible fumes, tap 

 smartly on the covered side, a vortex ring may be 

 clearly observed sailing through the air.| Its pro- 

 perties are interesting. In the first place, it has 

 become differentiated from the rest of the air by the 

 application of external force of which it has become 

 the embodiment. It has remarkable stability ; the 

 core is elastic and possesses rigidity. When one 

 Vortex vortex ring impinges on another they are deflected 

 in their course, and vibration occurs. It is on some- 

 what similar lines that atoms are supposed to be 

 formed, and hence they are called vortex atoms. 



* Lodge, ' Modern Views of Electricity,' p. 416. 



t Lodge, loc. cit., p. 412. 



I Wurtz, ' The Atomic Theory,' pp. 326-328. 



