504 SCIENCE PROGRESS. 



" The arguments of those who plead for the existence 

 of infinitesimal units, whether micellae or pangenes or 

 biophors or what not, amount to this : so far we have 

 been able to observe with our senses, but the things which 

 we have observed remain unintelligible to us ; reason tells 

 us that behind all this there must be something which we 

 are at present unable to observe, and analogy leads us to 

 believe that this is in the form of material particles ". 



Such conceptions are necessarily unsatisfactory for the 

 following reason : In the various activities commonly called 

 "vital," we can perceive various parts of an organism 

 under successively different conditions ; but the activities 

 themselves, whatever may be their nature, are not also 

 material bodies and are utterly imperceptible to our senses. 

 Now we can never imagine anything of which we have had 

 no sort of sensuous experience. Biophors, micellae, inotag- 

 mata, pangenes and molecules, are terms for mental images 

 of material particles which differ only from bodies percep- 

 tible to the senses, because they are supposed to be of 

 exceedingly minute size. They are, therefore, necessarily 

 incapable of making us understand anything immaterial, and 

 the use of them amounts to an attempt to make imaginary 

 representations of things perceptible to the senses serve as 

 representations of things imperceptible to the senses and 

 therefore essentially incapable of any such representation. 



The irrationality of this is very often unnoticed, because 

 the imagination of an immense multiplication and complica- 

 tion of minute parts and their motions, tends so to fatigue 

 the fancy as to make some persons think that by having 

 had their imagination thus overwhelmed by a complication 

 of images exceeding its grasp, they have arrived at some- 

 thing of a really different nature and capable of explaining 

 phenomena the senses can take cognisance of. 



Can we attain to any more satisfactory explanation, 

 or must we sit down contented, or discontented, with the 

 assertion of epigenesis as a fact ? 



We have seen Mr. Bourne himself affirm that reason 

 declares the existence of something else behind what we 

 can observe. 



