SOCIAL ECONOMY. 225 
The larger larvee retain their hold on, and move 
up and down, in their cells by means of a peristaltic 
action ;* by which also respiration is maintained. 
But for this it is necessary that the larva should 
quite fill the cell, or at least be in contact with two 
opposite walls. Now, the larve when they are about 
to change their position in the cell are much too 
small to hold themselves up in this manner. The 
only way in which they could touch two opposite 
sides of the cell at the same time would be by 
stretching themselves across it lengthwise. I cannot 
say whether the points of alternate attachment for 
the sucker and the mandibles, on this journey, are 
found on the same or on opposite sides of the cell, 
whether the larva climbs like a caterpillar, or some- 
thing like a chimney-sweep. For I never observed 
them travelling, but I have often found them pre- 
paring for the journey, the larva having turned on 
its pivot, so that its head was directed to the bottom 
of the cell. 
And now, this perilous journey safely accomplished, 
the larva feeds more greedily and grows larger day 
by day, in preparation for its transformation into a 
pupa. This preparation dates from the moment 
that it has reached the bottom of the cell. Arrived 
here it at once begins to weave the silk lining which 
is to protect it from external influences during the 
pupal stage. Were the formation of this web de- 
layed to a later period, the size of the larva would 
* Mr. Newport, ‘ Trans. Entom. Soc.’ Vol. III, p. 189, sup. cit. says, 
from personal observation, that the hornets maintain themselves in their 
cells by a vermicular movement. When the larva has travelled thus 
to the mouth of the cell, it makes a sudden longitudinal contraction 
of its whole body, and thus regains its position at the base of the cell, 
Q 
