THE HEREDITY OF ACQUIRED CHARACTERS IN PLANTS. 81 



potency we know nothing, and at present can conceive nothing ; though 

 of the fact of characters acquired through the soma, i.e. by the vegetative 

 organs, being subsequently hereditary, there is universal evidence. It 

 may be added that it is perfectly inconceivable how Evolution could 

 proceed a step if it were not so ; and that Darwin was undoubtedly right 

 when he regarded inheritance as a sine qua non in the origin of species. 

 Dr. Weismann was right in saying, " My theory rests upon theoretical 

 considerations," but wrong when he added, " and the want of any actual 

 proof of the transmission of acquired characters." 



It is sometimes urged that there is no proof that mutilations and 

 injuries, whether to the animal body or to trees &c, are hereditary. 

 Fortunately for man, they are not ; but even if they were, they are all 

 beside the question of Evolution. What one is looking for as being 

 hereditary are useful adaptations acquired by the soma, which fit the 

 plant or animal to its new environment better than the parental 

 structures ; or else they are organs which become degenerate, as boughs 

 turn to spines in drought, supportive tissues tend to disappear in submerged 

 plants, and floral organs become " rudimentary." 



Mutilations, injuries, or diseases are not favourable or useful variations 

 of structure, nor are they natural degenerations. Hence all references 

 to such have nothing whatever to do with acquired variations which 

 a systematist regards as characteristic of varieties and species. 



G 



