MODIFICATIONS AND VARIATIONS 177 



among organisms whose conditions of life seem absolutely identi- 

 cal. We refer them to changes in the germinal material before 

 or during fertilisation. We call them endogenous, constitutional, 

 blastogenic ; and there is no doubt that they are transmissible, 

 though they are not always transmitted. 



Is there really an Antithesis? — Some subtle minds have 

 found satisfaction in maintaining that the distinction between an 

 acquired modification and an inborn variation is a distinction 

 without a difference. In his interesting Problems of Biology 

 Mr. George Sandeman points out that every acquired quality 

 is congenital (i.e. there are in the organisation the rudimental 

 possibilities of it), and that every congenital quality is also 

 acquired (i.e. it requires to be nurtured by appropriate con- 

 ditions if it is to develop). In this epigram there is undoubtedly 

 truth, but is it relevant ? 



No doubt the possibility of the modification must be in the 

 organism, just as the possibility of an explosion is in the barrel 

 of gunpowder. The environment is not creative ; yet, as a matter 

 of fact, it seems possible to distinguish between the actual 

 modification which we see and measure and the possibility of it 

 which we presuppose. 



Similarly, it is very true that the potentialities so marvellously 

 embodied in the fertilised egg-cell require appropriate environing 

 conditions if they are to be realised, for, as His observed long 

 ago, "it is a piece of unscientific mysticism to suppose that 

 heredity will build up an organism without mechanical means." 



The common jelly-fish (Aurelia aurita) often has a pentamerous 

 instead of a tetramerous symmetry. This is a variation of 

 germinal, endogenous origin. Of course it requires an environ- 

 ment to develop in, but we cannot causally relate the structural 

 peculiarity to any peculiarity in the environment. It seems 

 to be logically quite distinguishable from a modification. 



Discussing words is often indescribably tiresome, but it is better 

 than misunderstanding them. " Inheritance of acquired characters " 



12 



