192 On the Uses of the Dorsal Vessel. [March, 



therefore made new dissections. The loaista gygantea being the 

 largest insect in Europe, 1 made it the subject of my new observa- 

 tions ; but I was not more fortunate in that species than I had been 

 in the preceding. The same thing happened with the locusta hre- 

 vipennis, verrucivora, grisea, gryllus liveola, and migratorius. 

 Though all these species are ot a considerable size, I tried new dis- 

 sections on the Idatia occidentalism acheta campestris, empusa pau- 

 perata, and mantis religiosa. In all these I found the dorsal vessel 

 without any ramification ; and what assured me of this was, that 

 after removing it with the greatest care, I could perceive no trace of 

 rupture, which would have been the case if it had been torn from 

 the ramifications of that vessel. No liquid was ever seen to run out; 

 but this, as we shall show hereafter, might depend upon a variety 

 of circumstances. 



But it was necessary to verify the observations of Com})aretti. 

 For that purpose I examined the dorsal vessel in a great number of 

 hdterjlies, tenehrios, and crickets. All these dissections confirmed 

 the results that I had already obtained. The same was the case 

 when I studied the organization of the sphinx, noctiia, and tclli- 

 gonia, all of them insects of a large size. It remained to be seen 

 whether the dorsal vessel of flies and of syrphus presented any 

 ramifications, as Comparetti has described such with considerable 

 detail. 1 saw in general in the dipterte and hymenopterae the dorsal 

 vessel exhibiting nun)erous contractions ; but 1 was never able to 

 perceive either vessels or pulsations along the side of the dorsal 

 vessel. Yet I studied this vessel in the scolia Jlavifrons, apis 

 violacea, and syrphus hifasciatus of Panzer, the largest species to 

 be found in the south of France. I then took the apis mellijica, 

 which Comparetti mentions expressly. Though the research in this 

 case was more diihcult, on account of the smallness of the species, 

 I did not perceive the cylindrical vessels, of which that anatomist 

 speaks, and which according to him proceed from the extremity of 

 the dorsal vessel, one going to the upper part of the body, the other 

 to the lower. Tiiough the disposition here mentioned by Compa- 

 retti indicates the regular course of a vessel, I still believe he was 

 deceived by the appearance of the hepatic vessels. 



I terminated these first researches by the examination of the larvae 

 of the lepidopterie. I chiefly dissected those of the sphinx, of the 

 tithymale, and of the bombyx of the mulberry. All these larvse 

 appeared to me to have a dorsal vessel without any kind of ramifica- 

 tion. I sought likewise to discover some traces of vascular vessels in 

 the cellular or muscular coats of the intestines — coats which certainly 

 would have received them if any had existed, for it is very well 

 known that the digestive apparatus is very distinct in larvee. The 

 muscles of the mandibles, examined with the same design, appeared 

 equally destitute of all vestiges of vessels, with whatever care I 

 examined them. 



These facts prove that the dorsal vessel in insects is a canal almost 

 cylindrical, only a little tapering at its two extremities. Its con- 



