126 MR. NEWPORT ON THE ORGANS OF REPRODUCTION, 



body, and from the interior of the colon. To effect this, the animal, which has pre- 

 viously been lying coiled up in a circular form, first straightens its whole body ; it 

 then forcibly contracts and shortens its body, especially at the posterior part, and by 

 this means becomes greatly enlarged in bulk at its middle portion, but smaller at its 

 extremities. During these efforts, which are some of the most powerful it is able to 

 make, the skin becomes loosened from its posterior parts, and while still contracting 

 its segments, the anal extremity, and with it the lining of the colon, become entirely 

 detached, and from these it gently withdraws itself within the old skin in which the 

 body is incased, as from the finger of a glove. This is precisely what takes place in 

 the shifting of the skin in insects. Having effected this part of its labour, all the 

 posterior segments are again shortened, the animal again disposes itself in a circular 

 form, and after repeated exertions succeeds in bursting the tegument of the head in 

 the part just described. As in the case of true insects, the young lulus entirely 

 empties the alimentary canal by voiding its faeces, and ceasing to eat for one or two 

 days preparatory to undergoing each transformation. When examined immediately 

 before the change, there are no other symptoms of new legs than slight elevations of 

 the skin, and this perhaps accounts for the length of time occupied in the change, the 

 new legs requiring time for further development before the old skin is thrown off. 



When these changes have been effected, the animal again arranges its legs along 

 the ventral surface of the body, and coils itself up in a circular form, in which state 

 it remains for several hours, often with the skin partially covering the posterior seg- 

 ments. In these transformations, as in those of insects, the whole of the structures 

 undergo alteration ; the lining membrane of the colon and lower intestines comes 

 away attached to the posterior, as that of the mouth and oesophagus does to the ante- 

 rior part. It is not, therefore, by the bursting of the skin on the under surface of the 

 anterior segments that the change is effected, as stated by Waga, but by a separation 

 of the natural sutures of the covering of the head. Indeed it is almost impossible to 

 conceive how the legs of the thorax and covering of the mandibles could be thrown 

 off if the change took place as stated by Waga. 



It has been supposed that the lulus devours its cast skin, as is done by some larvae 

 of insects. I certainly have seen it nibbling at the skin some hours after the change, 

 but although there were several cast skins in the vessel, and no food, there seemed 

 no disposition on the part of the animal to devour it. 



The^fth period of development being now attained, the young lulus has three ocelli 

 on each side of the head, seven joints to the antennae, thirty-four legs, and twenty- 

 one segments to its body. 



On the forty-eighth day (fig. 21.) the young lulus has entered this period, and ex- 

 hibits a marked alteration in its appearance. The antennae are considerably longer 

 than the head, with seven distinct joints, and, as in the adult, the apical one is 

 short and inserted into the sixth. The length of these organs has been increased 

 chiefly by the elongation of the second basilar joint, which is now narrower and 



