414 ON SUPPOSED BOTANICAL PROOFS OF [VII. 



the body {soma) of the plant may also influence the sexual cells. 

 If the apical shoot of a young spruce fir be cut off, one of the 

 lateral shoots of the whorl next below the section rises and 

 becomes an apical shoot : it not only assumes the orthotropic 

 growth of such a shoot, but also its mode of branching. The 

 phenomenon itself is well known, and I have often observed it 

 myself in my garden without making any botanical experiments ; 

 for this experiment is not uncommonl}^ made by Nature her- 

 self, when the apical shoot is destroyed by insects (for example 

 the gall-making Chermes). The change of the lateral into an 

 apical shoot occurs here in consequence of the loss of the true 

 apical shoot, and is therefore really dependent upon it. The 

 only difficulty is to understand how these and many other 

 kindred phenomena can be considered to prove the transmission 

 of acquired characters. That correlation exists between the 

 parts of an organism, that correlated changes are not only 

 common but nearly always accompany some primary change, 

 has been perfectly well known since Darwin's time, and I am 

 not aware that it has been disputed by any one. I further 

 believe that hardly any one would maintain that it is impossible 

 for the reproductive organs to be influenced by correlation. 

 But this is very far from the admission that such changes would 

 occur in the germ-cells as would be necessary for the trans- 

 mission of acquired characters. For such transmission to 

 occur it would be necessary for the germ-plasm (the bearer of 

 hereditary tendencies) to undergo a transformation correspond- 

 ing to that produced by the external influences ; — such a trans- 

 formation as would cause the future organism to spontaneously 

 develope changes similar to those which its parent had 

 acquired. But since the germ-plasm is not an organism in the 

 sense of being a microscopic facsimile which only has to 

 increase in size in order to become a mature organism, it is 

 obvious that the developmental tendencies must exist in the 

 specific molecular structure, and perhaps also in the chemical 

 constitution of the germ-plasm itself It therefore follows that 

 the changes in the germ-plasm which would be required for 

 the transmission of an acquired character must be of an entirely 

 different nature from the change itself acquired by the body of 

 the parent plant : and y^t it is supposed that the former is 

 produced by the latter as a result of correlation. I will illustrate 



