256 CLASS VIII. 
opinion of most writers of the present day, that they correspond to 
the kidneys of the higher animals, whence the term used above 
p- 254, (vasa “urinaria) for these vessels. Besides other grounds for 
this opinion, it is supported by chemical investigation!. These 
vessels appear to be present in all Insects, with the exception of 
Aphidii amongst the Hemiptera, where it has not been possible to 
find a trace of them. ‘Their number is very different, and seems 
to be on the whole inversely proportional to their length; they are 
short and very numerous, more than twenty, in the Hymenoptera and 
Orthoptera, and in Libellula and Ephemera amongst the Neuroptera. 
Here they are arranged in a ring round the intestinal canal which 
they perforate, whilst at the free extremity they terminate ccecally. 
In Gryllotalpa and Acheta F apr. they fall into a common canal before 
opening into the intestine. In the remaining Insects there are 
usually only four or two of them present (Diptera, Hemiptera, 
many Coleoptera), or six, as in other Coleoptera (the Heteromerata, 
Tetramerata, and Trimerata). When there are only two, they 
form a loop on each side of the intestinal canal, which seems to 
arise from the fusion of two vessels; and so open by four termi- 
nations into the canal. In those Coleoptera which have six, they 
are also attached to the inferior extremity of the intestinal canal 
(the Rectum), but do not open into it there; they run upwards as 
very fine vessels between the coats of the intestine and terminate 
blindly ?. 
If we consider these organs as Kidneys it becomes uncertain 
whether Insects have a Liver; for the idea that these vessels may 
represent at once both Kidneys and Liver (whence it has been 
proposed to name them vasa urino-biliaria) is not, as appears to 
me, the result of comparative investigation either anatomical or 
1 See Renecer’s Physiologische Untersuchungen tiber die thierische Haushaltung der 
Insecten, Tubingen, 1817, 8vo. Comp. WurzEr, Chemische Untersuchung des Stoffes, 
welcher sich in den sogenannten Gallengefiissen des Schmetterlings der Seidenrausse 
befindet in MecKEt’s Archiv. Iv. 1818, s. 213215. Also CHEVREUL found in the 
matter of these vessels potass, ammonia and wric acid; see STRAUS Considerations 
générales sur V Anatomie des Anim. articulés, auaquelles on a joint V Anat. descriptive du 
Melolontha vulgaris. Paris, 1828, 4to, p. 251. In a ZLucanus little stones have been 
found in these canals consisting of wric acid. Aupouin Ann. des Sc. nat. 2e Sér. 
Tom. v. 1836, p. 129. C. VERLOREN found in larve of Lepidoptera (Sphinx ligustri) 
no wric acid in these vessels, but hippuric acid, as he informed me by letter in 1843. 
2 Léon Durour, Mém. sur les vaisseaux biliatres des Insectes. Ann. des Sc. net. 
2e Série, Tom. xtx. 1843, pp. 145—182, Pl. 6—9. 
ae 
