122 
MR. NEWPORT ON THE ORGANS OF REPRODUCTION, 
equal in size and length to the original ones, but were evidently more feeble. The 
transverse markings on the seven anterior segments (2. 7.) were very distinct, and the 
large brown patch (jp) on the seventh segment was much darker in colour. The whole 
body of the animal was considerably elongated. This was produced chiefly by the 
extension of the new segments (7-f) formed from the germinal membrane at the 
posterior part of the seventh, and which, in the early part of the last period, seemed 
to form a single distinct segment covered by the common tegument. The most 
anterior of these new segments (8.), now the eighth of the whole body, had acquired an 
extent equal on its upper surface to the preceding segment, but was shorter on its 
ventral surface. Like the preceding original segments, it was divided into two re- 
gions by a transverse depressed line. The next segment in succession to this, the 
ninth, had also become enlarged to about one-third of the eighth, and was like it 
marked transversely. The next four segments were each more developed than in the 
preceding state, but not to so great an extent as the others. The two remaining seg- 
ments (14. 15.), the penultimate and anal, had undergone no change. They had 
simply acquired a little extension at the apex of the segment, and were now covered 
with a few scattered hairs. It is thus proved that the body is elongated, not by the 
division of already formed segments into others, but always by the formation of new 
ones in the germinal membrane that extends from the posterior margin of the ante- 
penultimate segment, to the penultimate, which last segment, with the anal, undergoes 
no change. That segment is always furthest advanced which is immediately poste- 
rior to the last segment that possesses legs ; and then the next in succession, until we 
arrive at the terminal ones, the penultimate and anal, which never bear legs. The 
body of the lulus is thus formed of fifteen segments. In this respect it affords a 
further analogy to those already pointed out with the larva of insects at their first 
coming from the egg, only that the lulus is one grade lower. The usual number of 
segments in insects is thirteen, but this is not constant. It varies in accordance with 
the higher or lower state of development of the species. Thus, in some, the thir- 
teenth is only a very rudi mental one, even less developed than the fifteenth at this 
period in lulus. But in some of the apodal larvae, which approach closely in their 
rudimental condition of development to lulus, the number is fourteen, besides a mi- 
nute anal tubercle, analogous to the anal or fifteenth of lulus. This has already been 
elsewhere shown both by Westwood* and myself-f*, and seems to confirm the view 
here advanced with regard to the comparative development of these animals ; though 
in lulus all the segments are double. 
On the twenty-eighth day I found all the specimens, now in the fourth period of 
development, still lying collected together. On moistening the soil in which they 
were placed, they soon moved briskly their antennae, as if seeking nourishment ; their 
motions were still exceedingly feeble. This could not have arisen from too reduced 
* Transactions of the Entomological Society, vol. ii. p. 124. 
t Cyclopaedia of Anatomy and Physiology. Insecta, vol. ii. p. 871. 
