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 _Armadillidium 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 so in fact, that any of his species that happen to find him will attack him and eat all his front half, rejecting, however, his now hardened tail-end. Provided that the moulting woodlouse has survived (and in captivity, to ensure this, he must be isolated), after three days his jaws will be sufficiently hardened to allow of his eating, and usually he first of all devours the second half of his cast skin. The operation of moulting does not occupy quite so long a time in the case of young examples. Specimens half-an-inch long do not moult more than once in six months and show but little increase in size after the process.