THE BRITISH WOODLICE. 13 
just sufficient difficulty in doing this successfully to give an 
interest to the matter. 
Apart from a supply of proper food, we take it that the chief 
object to be attained is the provision of the amount of moisture 
required by the particular species under examination, together 
with a sufficient supply of air. 
A great many interesting observations can be thus carried 
out, such as those of Mr. Casserley, to which allusion has already 
been made. The process of moulting for instance is well worth 
watching, and although specimens with half their coat changed 
may be found in remote corners, yet the whole course of the 
moult can be seen much better in the case of captive woodlice. 
The following account is taken from Mr. Casserley’s description 
(75) of what happens in the case of Avmadillidium vulgave:—The 
approach of the moult is indicated by the appearance of a white 
border on each segment of the body, which becomes gradually 
more marked, while at the same time the animal is seen to be 
less active and often makes a small burrow in which to hide. 
Sometimes a sheltered corner against a stone is looked upon as 
affording sufficient protection, but_in either case each woodlouse 
keeps to the place originally chosen. About ten days after the 
white lines have become visible the animal appears to be divided 
into two. Its skin is becoming loose and little movement can 
take place at the joints of its body with the exception of that 
between the fourth and fifth thoracic segments where the skin 
will ultimately break. The woodlouse spends a day or two in 
this condition and then, by suddenly walking forward, frees itself 
from the covering of the hinder portion of its body The three 
last pairs of walking legs are carefully pulled out from the old 
skin, which now appears perfectly white, and at the same time 
the lining of the hind portion of the alimentary canal (hind gut) 
is also shed. After putting the tender half of his body weil into 
his corner or burrow the woodlouse proceeds to eat the part of 
his skin that he has cast. The creature has now a very odd 
appearance. His front half with the exception of the white 
edges is as it was before, the rest of him instead of a light slaty 
blue, and is very soft as well as proportionately a little larger. 
In three days or so the tail end becomes hard and attains the 
normal colour. Then the old skin from the front half is pushed 
off and the creature becomes practically defenceless, so much 
