118 MR. NEWPORT ON THE ORGANS OF REPRODUCTION, 



cumstances explain the cause of the very quiescent state of the young lulus, and its 

 almost, and perhaps entire abstinence from food while this skin remains on its body. 

 It is not until this skin is thrown off that the new segments become elongated, and 

 the lulus then appears suddenly to have acquired six new divisions to its body. The 

 production of new legs is equally curious. Up to the present period the animal has but 

 six legs (6. a). But four additional pairs are nevertheless in the course of formation. 

 These at present exist only as eight minute nipple-shaped prominences on the under 

 surface of the sixth and seventh segments (b, c), four on each, covered by the common 

 tegument, which we have seen' is becoming deciduous. The three single pairs of legs 

 that now exist as the only locomotive organs, are attached, one pair to the protho- 

 racic or second segment, one to the third, and one to the fifth segment. The fourth, 

 or segment intermediate between these, never possesses any legs, but in the female 

 contains the outlets of the organs of generation. In pursuing the analogies between 

 these segments and the thorax of insects, the first two seem to represent the pro- and 

 mesothorax, while the fourth and fifth becoming united, answer to the metathorax : 

 this is analogous to the fusion of the fourth and fifth segments in the changes of true 

 insects. The general appearance of the animal has now become less delicate, the 

 head has acquired a darker colour, and a faint broad brown patch (p) is now making 

 its appearance at the anterior part of the seventh segment. This patch, which is 

 permanent through all the earlier changes of the animal, is of the greatest utility in 

 determining the production of the new segments. It is in. the segment immediately 

 posterior to this that the male organs find their outlet, a circumstance the more re- 

 markable, from the fact that this outlet is in the anterior part of the original germi- 

 nal space, and that at the bursting of the egg this is very near the termination of the 

 body. This was the condition of the young lulus one hour (fig. 10.) after leaving the 

 amnion. It soon began to exhibit its animal powers, to show the instinct peculiar to 

 its species, and to be sensibly aff*ected by external causes. In less than six hours from 

 the bursting of the amnion, those specimens which had first undergone the changes 

 were in motion. At first the antennae were the organs employed. They were moved 

 slowly to and fro, and seemed to gain power by use ; in a short time the limbs be- 

 gan to be extended, and the animal slowly raised itself upon them for the first time. 

 Its first efforts at locomotion were exceedingly feeble, but it gradually gained 

 strength. At the end of twelve hours the whole of the embryos were in motion, 

 crawling about slowly, but moving the antennae briskly. On exposing them to a 

 strong light, a marked effect was produced in their movements. They evidently were 

 greatly affected by it, and seemed instinctively to shun it, retiring out of the way. 

 This was the first marked exhibition of instinct. Locomotion was at first performed 

 very slowly, but with instinctive care. The anal segment previously to each step was 

 expanded like the anal leg of the larva of an insect, and being first attached like a 

 true proleg, and its step, as it were, measured, its body was carried forwards by an 

 effort that extended, as in insects, from segment to segment. 



