168 SPECIES NOT 



Having thus, as he conceives, made out his 

 case, Mr. Darwin indulges in the following strain 

 of triumph: "The case is also very interesting, 

 as it proves that with animals, as with plants, 

 any amount of modification in structure can be 

 effected by the accumulation of numerous slight, 

 and, as we must call them, ACCIDENTAL VARIATIONS, 

 which are in any manner profitable, without 

 exercise or habit having come into play." 



It appears to me that Mr. Darwin has misin- 

 terpreted the fact that the castes of slaves in 

 the driver ant from North America are very 

 different from, and yet insensibly grade into each 

 other. He draws from this the singular infer- 

 ence in the last quotation but one. But tlir 

 question is simply, are these different forms pro- 

 duced as such by the ant, or are they modified 

 by food, and other treatment, just as the suspended 

 fecundity of the worker bee is re-established In- 

 feeding the larva with royal bread. It would be 

 altogether contrary to every known fact in re- 

 production, to suppose that these varieties could 

 be formed in any other way. In fact it may 

 be laid down as an impossibility that any animal 

 should produce a series of young which should 

 differ as the castes of these slaves are said to do. 

 Therefore the operation is one purely of instinct 

 on the part of the worker antS, and Mr. Darwin's 

 hypothesis falls to the ground. 



The singular light which has of late years been 

 thrown upon the law of reproduction, by the facts 

 of what is termed Parthenogenesis, may help to 



