HOW THE GREENBOTTLE DOES ITS DUTY 133 



materials, fresh and wholesome in every particular, and varied 

 enough, one would say, to suit the most fastidious taste. Such a free 

 lunch should tempt the most abstemious. 



During the day many greenbottles are attracted to the repast. They 

 find the lure attractive and satisfying to their own mature appetite, 

 but for all our trouble no eggs are laid upon the stores. This is 

 indeed mystifying. Can it be that such excellent provender is 

 unworthy of the fly's offspring? A curious state of affairs this, that 

 such a puny creature must reject the fats, sugars, proteids and other 

 nutrients capable of sustaining life in man himself. 



Let us collect our foods and place each in a separate test tube, 

 previously inoculated with a number of young flies. The youngsters 

 are not half so particular as their parents. They feed happily enough 

 on what we have provided and the tide of liquid rises rapidly in each 

 tube. The egg, the fruit, the dry gluten, all but the sugar are con- 

 sumed with relish by the maggots. 



We have seen that the mother greenbottle ignores these fresh 

 foods for the purpose of laying her eggs, but we know from the 

 experiment just performed that her young will thrive upon them. 

 Perhaps this is common knowledge between the fly and ourselves, yet 

 she selects only putrefying matter in which to bear the fruit of her 

 love, that our world may be saved from the menace of decay. 



No doubt the greenbottles carry germs, no doubt they bring an 

 occasional sickness to those who come in contact with them, but unlike 

 the house fly, they are at the same time altruists, working for the 

 public good. Like the street cleaner and the hobo, both are dirty, 

 yet one is a menace, while the other rids us of one. 



