72 MR. NEWPORT ON THE ANATOMY AND DEVELOPMENT 
leguminous plants, whilst the head of the little white larva was slowly passing out between 
them (14 a & b), like the germ-roots, to become affixed by its mouth to the skin of the cater- 
pillar, the body being retained within the shell. As the parasites became attached, the fated 
caterpillar moved about with increased rapidity, twisting and turning its body in every direc- 
tion, and evidently endeavouring to get rid of its new-born enemies, but to no effect. The 
little beings, securely affixed by their shells, giving no evidence of sensation, and scarcely 
even of vitality, were unaffected by these endeavours to displace them, and retained firm 
‘hold. The cleavage of the shell was chiefly on the under surface, so that the two halves 
formed a kind of bivalve covering or cloak to the larva, and clasped its body as the head 
emerged. The head at first was the only portion of the larva that was exposed. But 
the little creature grew rapidly, deriving its nourishment by slight puncture and suction 
through the skin of the caterpillar, with scarce an abrasion of the surface. The rapidity ` 
of its growth in this way was truly astonishing, the whole of the nutriment thus imbibed 
being appropriated to its increase, excepting only the very little expended by cutaneous | 
transpiration; for respiration at this early period can scarcely be proved to have com- 
menced, as I was unable at this stage to detect the respiratory organs, while the digestive 
cavity, as we have already seen in other parasites, was imperforate. Within £wo hours 
from the bursting of the shell there was a marked increase of size in the larva. In the 
course of the first day the prothorax and the head were extended from the shell, and early 
in the second day the three thoracic segments, as well as a large portion of its ventral sur- 
face, were exposed, the larva (fig. 15) then being nearly twice its original size in the ovum. 
When examined by a lens it seemed to be almost entirely formed of an immense stomach, 
connected with the mouth by a short and very narrow cesophagus, as in the larva of Mono- 
dontomerus. The motions of the stomach, vermicular and incessant, were distinctly seen 
through the tegument. As the insect increased in size, it was more and more extended 
from the shell. Its anterior part grew the most rapidly, the largest segment being the 
first, or prothoracic. 
It was not until after the completion of the second day that I was able to detect the 
respiratory organs through the tegument, although I had previously sought for them with 
much care. The little vegetating being then seemed like an embryo, which,— instead of 
deriving its means of growth, like other embryos of its class, in the unburst egg by imbi- 
bition of fluid from without, through its shell and membranes,—had been prematurely 
exposed by the sudden rupture of its envelope, and left to perish, or to absorb adventitious 
nourishment from other bodies. I could not help regarding it among insects as the 
representative of the embryo Kangaroo among quadrupeds, prematurely liberated from its 
foetal coverings, and extruded from the body of its parent, to continue existence attached 
externally to the teat in the marsupium. But still more closely did it resemble the em- 
| bryo of the inferior Myriapoda,—the Iulide, in which the young, after bursting its shell 
longitudinally, as in Paniscus, is detained within it, and continues to grow by imbibition 
of nourishment through its membranes from the surrounding medium. There is, how- 
ever, this difference. In the Zwlide the retained embryo is inclosed in its membranes 
piis NE and does not throw them off until it has acquired organs of loco- 
is. o move about and seek food. But the young Paniscus bursts its 
