AUGUST 209 



sphere suffices to work further change. The body 

 darkens to sooty black, the wings expand into gauzy, 

 glittering structures, the forehead hardens, and the com- 

 pound eyes develop precocious vigilance. The maggot, 

 which was an almost featureless cylinder divided into 

 thirteen segments, has now got 'a waist,' and a figure 

 elegantly shaped into head, thorax, and abdomen, with 

 six serviceable legs furnished with patent soles or plan- 

 tulce, enabling the owner to defy the laws of gravitation 

 when it desires to walk upon vertical or inverted polished 

 surfaces. The other most notable organs which it has 

 acquired during pupation are a pair of lovely wings; a 

 pair of organs behind these, called halteres, which some 

 consider to represent rudimentary posterior wings, but 

 which others regard as being connected either with 

 respiration or with hearing ; a long and complex pro- 

 boscis, formed for suction ; and a pair of compound eyes 

 of extraordinary vigilance and keenness, enormous in 

 proportion to the size of the creature. 



As aforesaid, the mother fly lays but four or five score 

 eggs in a setting, which is a trifling performance in com- 

 parison with the fecundity of many other insects; but 

 whereas she repeats the process three or four times 

 during her life of a few months, and that her offspring 

 take up the same game immediately after passing through 

 metamorphoses occupying less than three weeks, it has 

 been calculated that one female house-fly may be the 

 source of a posterity numbering about two millions in a 

 single summer. 



The diet of the perfect fly is far more varied than that 

 of the maggot whence it sprang. Every grade of society 

 is open to it ; its tastes are catholic ; it may satisfy its 

 o 



