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PERIPATUS, MYRI0P0DS, AND INSECTS. 



ness of females to the elimination of the disadvantageously 

 conspicuous in the course of natural selection. There may 

 be truth in both views, but both require to be supplemented 

 by the consideration, in part accepted by Wallace, that the 

 " secondary sexual characters " of both sexes are the natural 

 and necessary expressions of their respectively dominant 

 constitutions. 



The organs consist of : — 



Some peculiarities in reproduction. — Many Insects, such as 

 aphides, silk-moth, and queen-bee, are exceedingly prolific. The 

 queen termite lays thousands of eggs, "at the rate of about sixty per 

 minute" ! 



The store of spermatozoa received by the female, and kept within the 

 receptaculum seminis, often lasts for a long time, — for two or three 

 years in some queen-bees. Sir John Lubbock gives the remarkable 

 instance of an aged queen-ant, which laid fertile eggs thirteen years 

 after the last union with a male. 



Parthenogenesis, or the development of ova which are unfertilised, 

 occurs normally, for a variable number of generations, in two Lepido- 

 ptera and one beetle, in some coccus insects and aphides, and in certain 



