THE BRITISH WOODLICE. 51 



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 vulgare: — 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 well 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 



