SOCIAL ECONOMY. ° 221 
of her nest. As fast as each cell takes shape she 
deposits an egg in it, generally on the inner side of 
the pouch, and in a corner, firmly glued to the wall. 
When the cell has been used before it is of course 
lined with the cocoon of the previous inmate. This 
makes no difference in the adhesion of the egg, as 
the glutinous secretion in which it is enveloped 
penetrates the lining, and fastens the egg through it 
to the paper wall. But the height of the wall makes 
a difference as to the position of the egg in the cell, 
for, as the mother-wasp can only reach to a certain 
distance with her abdomen, the egg is fixed nearer 
the mouth of the cell when this is an old one, than 
when she follows close on the traces of the workers, 
and deposits the egg before the cell-walls have been 
built up to their full height. 
The egg stands out obliquely from the side of the 
cell, as a little white speck about half a line long, 
and in this position it hatches. The larva, however, 
is not immediately set free from confinement on 
hatching, for the tail remains fast within the egg- 
shell. On this centre the larva moves freely; it 
feeds and grows, but cannot get away from the spot 
on which the egg was laid. The vertical direction 
of the cells makes this provision necessary, for a 
moment’s consideration will show that, without it, 
as soon as the larvee were hatched they would fall 
out of their cells and die. The embryo wasp has, 
even at this early period of its existence, a pair of 
mandibles, distinguished from the pair which it next 
acquires by the greater length of the central tooth, 
and mounted on a horny frame very like the bows of 
a pair of spectacles. These deciduous mandibles are 
