which they have passed and on every side by the
thickness of the vessel's contents. Satisfied with the site, they have
stopped there.

It is a very different matter in the tube. The least buried of the pupae
are half a yard down. Others are lower still; most of them even have
reached the bottom of the tube and are touching the cork stopper, an
insuperable barrier. These last, we can see, would have gone yet deeper
if the apparatus had allowed them. Not one of the score of grubs has
settled at the customary halting place; all have traveled farther down
the column, until their strength gave way. In their anxious flight, they
have dug deeper and ever deeper.

What were they flying from? The light. Above them, the column traversed
forms a more than sufficient shelter; but, at the sides, the irksome
sensation is still felt through a coat of earth half an inch thick
if the descent is made perpendicularly. To escape the disturbing
impression, the grub therefore goes deeper and deeper, hoping to obtain
lower down the rest which is denied it above. It only ceases to move
when worn out with the effort or stopped by an obstacle.

Now, in a soft diffused light, what can be the radiations capable of
acting upon this lover of darkness? They are certainly not the simple
luminous rays, for a screen of fine, heaped up earth, nearly half an
inch in thickness, is perfectly opaque. Then, to alarm the grub, to warn
it of the over proximity of the exterior and send it to mad depths
in search of isolation, other radiations, known or unknown, must be
required, radiations capable of penetrating a screen against which
ordinary radiations are powerless. Who knows what vistas the natural
philosophy of the maggot might open out to us? For lack of apparatus, I
confine myself to suspicions.

To go underground to a yard's depth--and farther if my tube had allowed
it--is on the part of the Flesh fly's grub a vagary provoked by unkind
experiment: never would it bury itself so low down, if left to its own
wisdom. A hand's breadth thickness is quite enough, is even a great deal
when, after completing the transformation, it has to climb back to the
surface, a laborious operation absolutely resembling the task of an
entombed well sinker. It will have to fight against the sand that slips
and gradually fills up the small amount of empty space obtained; it
will perhaps, without crowbar or pickaxe, have to cut itself a gallery
through something tantamount