The Grey Flesh-Flies 



this screen reigns utter darkness, the buried 

 one's delight. This is capital. 



What would happen if, by an artifice, the 

 sideward layer were nowhere thick enough to 

 satisfy the grub ? Now, this time, I have the 

 wherewithal to solve the problem, in the shape 

 of a big glass tube, open at both ends, about 

 three feet long and less than an inch wide. I 

 use it to blow the flame of hydrogen in the 

 little chemistry-lessons which I give my child- 

 ren. 



I close one end with a cork and fill the tube 

 with fine, dry, sifted sand. On the surface of 

 this long column, suspended perpendicularly 

 in a corner of my study, I install some twenty 

 Sarcophaga-grubs, feeding them with meat. 

 A similar preparation is repeated in a wider 

 jar, with a mouth as broad as one's hand. 

 When they are big enough, the grubs in either 

 apparatus will go down to the depth that suits 

 them. There is no more to be done but to 

 leave them to their own devices. 



The worms at last bury themselves and 

 harden into pupae. This is the moment to 

 consult the two apparatus. The jar gives me 

 the answer which I should have obtained in 

 the open fields. Four inches down, or there- 

 abouts, the worms have found a quiet lodging, 



245 



