368 The Unity of the Organism 



because of their resemblance to the corresponding parts in 

 the parent organism are manifestations of heredity, the 

 "indifferent protoplasm" which gave rise to the parts is 

 more certainly a "physical basis of heredity" than would 

 be any extraneous part or substance that might be shown to 

 "influence" the substance which itself transforms into the 

 parts. 



The essence of my contention may be briefly stated thus : 

 recognizing as every biologist must, that transformation is 

 an absolutely indispensable element of organic development, 

 when the transformation of an "indifferent mass of proto- 

 plasm" into definite organs or parts takes place before our 

 eyes, we are bound by principles of objective science to be- 

 lieve that the transforming substance itself is actively ai 

 not entirely passively concerned in the operation. We ai 

 thus bound since, by supposing that if we cannot "causally 

 explain" the observed process we must assume that the ret 

 cause, the ultimate explanation, lies deeper and in soi 

 other substance, we are committing ourselves to a coui 

 which, if consistently followed, denies the validity of all ol 

 servational knowledge. Such repudiation would result froi 

 the fact that as soon as we succeed in bringing the "othei 

 substance" under observation we are always confronted witl 

 the same difficulties as to causal explanation which we met 

 in the first instance. In observing a cause, or the "seat' 

 of a cause, in actual operation, we are never able to satisfy 

 ourselves as to exactly how or why it operates as it does. 

 Supposing, for example, we were able to see the atoms or 

 even the electrons of nitrogen, carbon, oxygen and so on, at 

 their work in producing membranellae in Stentor, does any 

 one suppose we should be able to see fully why and how they 

 do it? Who in modern times refuses to believe that the force 

 of gravitation is partly inherent in the earth itself and in 

 every other body, though no amount of examination of the 

 bodies can make out fully how and why the bodies have 



