COMPENSATION AND ECONOMY OF GROWTH. 139 



selection some one modification in structure, and, after 

 thousands of generations, some other and independent 

 modification; and these two modifications, huvin^^ been 

 transmitted to a whole group of descendants witli diverse 

 habits, would naturally 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 impossibihty 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. 



COMPE]^SATIOK AJ^D ECONOMY OF GROWTH. 



The elder Geoff roy 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 hardlv be maintained that the law is of uni- 

 versal application; but many good observers, more espe- 

 cially botanists, believe in its truth. I will not, however, 

 here give any instances, for I see hardly any way of distin- 

 guishing between the effects, on the one hand, of a part 

 being largely developed through natural selection and 

 another and adjoining part being reduced by the same pro- 

 cess or by disuse, and, on the other hand, the actual with- 

 drawal of nutriment from one part owing tc the excess of 

 growth in another and adjoining part. 



