NEUTER INSECTS. 217 



ot:uter insects. 



By CHAELES MOEEIS. 



IN the later editions of Darwin's " Origin of Species " he has an- 

 swered with remarkable ability nearly all of the several weighty 

 arguments brought against his theory. Some seemingly insuperable 

 objections have been met with an array of facts before which they 

 quite break down. Thus, several instances of extraordinary organs in 

 certain species or types of animals, which it was claimed could not 

 possibly have originated through natural selection, he has shown to be 

 connected by intermediate variations with ordinary organs, which va- 

 riations are useful at every point of their development, so that the 

 strange appendages might easily have arisen through minute grada- 

 tions of change. 



There is one objection, however, which he can scarcely be said to 

 have answered so happily. This is that in reference to neuter insects 

 — the specially developed working-ants, for instance. As he himself 

 acknowledges, the phenomenon of neuter insects appeared to him at 

 first insuperable, and actually fatal to the whole theory, since these 

 neuters often differ widely in instinct and structure from the males 

 and females, yet, being sterile, they are incapable of hereditarily rej^ro- 

 ducing their characteristics. In working-ants the difference from the 

 sexual forms is often very great, as in the shape of the thorax, the 

 lack of wings and sometimes of eyes, and in instinct. The difference 

 in instinct is still greater in the hive-bee. Nor is this the whole of 

 the difficulty. In some species of ants there are two and even three 

 distinct castes, well defined, and each with specialities of structure. 



Yet, as it is quite impossible that these sterile females could trans- 

 mit their peculiarities to descendants, and as no such peculiarities exist 

 in the structure of the males and developed females, hereditary influ- 

 ence would seem to vigorously oppose their reproduction, and it seems 

 quite extraordinary that the sexual forms should produce offspring so 

 markedly unlike them. The case is as remarkable as if the offspring 

 of a lion and lioness should be a cat or a leopard, or if a sheep should 

 produce an antelope. 



Darwin seeks to explain this difficulty by considering that selection 

 may apply to the family as well as to the individual, and that chance 

 peculiarities of structure, which proved useful to the community, may 

 have been preserved by selection, the tribes in which such useful aber- 

 rant forms appeared surviving, while tribes more normal in reproduc- 

 tive power perished. Illustrative facts tending in the same direction 

 are given, and there is certainly a degree of force in this argument, 

 though it can scarcely be accepted as wholly satisfactory. 



It is probable that Darwin did not give to this question as full a 



