COMPENSATION AND ECONOMY OF GROWTH. 131 



and which in truth are simply due to inheritance; for an 

 ancient progeaitor may have acquired through natural selec- 

 tion some one modification in structure, and, after thousands 

 of generations, some other and independent modification; 

 and these two modifications, having been transmitted to a 

 whole group of descendants with diverse habits, would nat- 

 urally be thought to be in some necessary manner correlated. 

 Some other correlations are apparently due to the manner in 

 which natural selection can alone act. For instance, Alph. : 

 de Candolle has remarked that winged seeds are never found 

 in fruits which do not open ; I should explain this rule by 

 the impossibility of seeds gradually becoming winged through 

 natural selection, unless the capsules were open : for in this 

 case alone could the seeds, which were a little better adapted 

 to be wafted by the wind, gain an advantage over others less 

 well fitted for wide dispersal. 



COMPENSATION AND ECONOMY OF GROWTH. 



The elder Geoffroy and Goethe propounded, at about the 

 same time, their law of compensation or balancement of 

 growth; or, as Goethe expressed it, "in order to spend on 

 one side, nature is forced to economize on the other side." 

 I think this holds true to a certain extent with our domes- 

 tic productions : if nourishment flows to one part or organ 

 in excess, it rarely flows, at least in excess, to another part ; 

 thus it is difficult to get a cow to give much milk and to 

 fatten readily. The same varieties of the cabbage do not 

 yield abundant and nutritious foliage and a copious supply 

 of oil-bearing seeds. When the seeds in our fruits become 

 atrophied, the fruit itself gains largely in size and quality. 

 In our poultry, a large tuft of feathers on the. head is gen- 

 erally accompanied by a diminished comb, and a large beard 

 by diminished wattles. With species in a state of nature it 

 can hardly be maintained that tho law is of universal appli- 

 cation ; but many good observers, more especially botanists, 

 believe in its truth. I will not, however, here give any 

 instances, for I see hardly any way of distinguishing between 

 the effects, on the one hand, of a part being largely devel- 

 oped through natural selection and another and adjoining 

 part being reduced by the same process or by disuse, and, on 

 the other hand, the actual withdrawal of nutriment from one 

 part owing to the excess of growth in another and adjoining 

 part. 



