74 BIOLOGICAL SOCIETY OF WASHINGTON. 



that fecundity does not determine the rate of increase ; that the 

 struggle for life is most severe between species of the same genus ; 

 that secondary sexual characters are generally displayed in the same 

 parts of the organization in which the species of the same genus 

 differ from each other; that distinct species present analogous varia- 

 tions ; that similar structures are often independently developed ; 

 the varying importance for classification of the same important or- 

 gan in the same group of beings ; that analogical or adaptive re- 

 semblances are misleading for classification ; that the great fre- 

 quency of mimicry among insects is associated with their small 

 size and general defencelessness, as no species furnished with a 

 sting, or other defensive property, is known to mimic other species ; 

 the importance of relative position or connection in homologous 

 parts ; the remarkable changes of structure effected during devel- 

 opment; that adaptation to the conditions of life in the insect 

 larva is just as perfect and beautiful as in the adult animal, and 

 that, consequently, larvae of different orders are often similar, and 

 larvae belonging to the same order often very dissimilar; that larval 

 and pupal stages are acquired through adaptation, and not through 

 inheritance ; that rudimentary organs plainly declare their origin 

 and meaning. 



Finally he brought together a large body of interesting facts 

 in entomology, bearing on the development and perpetuation 

 of mimicry, and of secondary sexual characters — all more or less 

 explicable by, and furnishing convincing argument for, the gen- 

 eral theory of natural selection ; while he freely acknowledged 

 that he found among insects facts that seemed to be most fatal to 

 the theory. This is especially the case in social insects where the 

 colony contains neuters and sterile females which often differ widely 

 in instinct and in structure from the sexual forms, and yet can- 

 not propagate their kind. This is not the place to-enter into a 

 discussion of the subject, and I will simply remark that there are 

 reasons for the belief that, in his candor, he has been led to exag- 

 gerate the difficulties in this case. 



