208 SECRETS OF ANYMAL LIFE 
delicate egg. So it is hung by a thread from the 
roof of the cupola, and after the Eumenes grub 
hatches, it makes the cast shell of the egg into a 
flexible staircase so that it can reach the caterpillars 
and bite them, yet retreat if they are too vigorously 
recalcitrant. This is perfection. 
The second point which Fabre’s observations 
illustrate very finely is the frequently serial char- 
acter of instinctive behavior. There is a particular 
sequence, and that sequence is adaptive. The 
Capricorn grub of the Cerambyx beetle burrows for 
three years on end in the depths of an oak tree. 
But when it is full-grown and the time of its meta- 
morphosis draws near, it moves to the periphery 
and makes a passage almost out, leaving only a 
film-like screen, just as if it knew that the winged 
beetle to emerge from the pupa-case would other- 
wise be buried alive. It then draws back a little 
in its gallery and makes an outer barricade of 
particles of chopped wood,and inside that an 
inner partition like a white skull-cap or acorn-cup, 
composed, strange to say, of carbonate of lime and 
some organic cement. The next step is to make 
on the side of the exit-way a_transformation- 
chamber. This is three or four inches long, and is 
padded “ with a fine swan’s down, a delicate pre- 
caution taken by the rough worm on behalf of the 
tender pupa.” The next step is to fall asleep and 
dream of becoming a beetle. ‘ The grub lays aside 
its tools, molts its cuticle and becomes a pupa, 
lying, weakness personified, on a soft couch. The 
