26 SOCIAL LIFE IN THE INSECT WORLD 



living spot in the wall is the fountain where the supply 

 of moisture is renewed. When its reservoir is exhausted 

 by the conversion of dry dust into mud the miner 

 descends to its chamber, thrusts its proboscis into the 

 root, and drinks deep from the vat built into the wall. 

 Its organs well filled, it re-ascends. It resumes work, 

 damping the hard soil the better to remove it with its 

 talons, reducing the debris to mud, in order to pack 

 it tightly around it and obtain a free passage. In this 

 manner the shaft is driven upwards ; logic and the facts 

 of the case, in the absence of direct observation, justify 

 the assertion. 



If the root were to fail, and the reservoir of the 

 intestine were exhausted, what would happen ? The 

 following experiment will inform us : a larva is caught as 

 it leaves the earth. I place it at the bottom of a test-tube, 

 and cover it with a column of dry earth, which is rather 

 lightly packed. This column is about six inches in 

 height. The larva has just left an excavation three times 

 as deep, made in soil of the same kind, but offering a 

 far greater resistance. Buried under this short column 

 of powdery earth, will it be able to gain the surface ? 

 If its strength hold out the issue should be certain ; 

 having but lately made its way through the hard earth, 

 this obstacle should be easily removed. 



But I am not so sure. In removing the stopper which 

 divided it from the outside world, the larva has expended 

 its final store of liquid. The cistern is dry, and in 

 default of a living root there is no means of replenishing 

 it. My suspicions are well founded. For three days the 

 prisoner struggles desperately, but cannot ascend by so 

 much as an inch. It is impossible to fix the material 



