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 two 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 oesophagus, as in the larva oiMono- 

 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, bike 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 Ifyriapoda, — the Iulidce, 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 Iulida? the retained embryo is inclosed in its membranes 

 after the shell is burst, and does not throw them off until it has acquired organs of loco- 

 motion and is able to move about and seek food. But the young Paniscus bursts its 



