OF MYRIAPODA AND MACROUROUS ARACHNIDA. 
273 
carried on, whether in vessels with distinct parietes, or in sinuses bounded by the 
other structures of the body, is still a matter of inquiry, and the existence of vessels 
in insects has recently been denied by no less an authority than Leon Dufour. 
Lyonet* himself, in his admirable work on the Anatomy of the Cossus, states that 
he could discover no vessels connected with the great dorsal vessel, which he believed 
to be closed, and to contain a fluid. This also was the opinion of Marcel de Serres, 
who regarded it as a structure for the secretion of fat. Cuvier also believed that 
this organ was entirely closed, and in consequence supposed that nutrition in insects 
is effected by simple imbibition. But so early as the year 1812, Treviranus, in his 
account of the anatomy of the Arachnida, pointed out the existence of vessels con- 
nected with the sides of the dorsal vessel in the Scorpions and Spiders; but stated that 
he was unable to determine whether they are arterial or venous-^. In a subsequent 
work in 1816^, he has stated that no vessels exist in the Tracheary Arachnida, a re- 
mark which Latreille§ repeated in 1831 ; and in 1817 1| Treviranus stated, that 
none exist in the Mvriapoda. But in 1825 Straus Burckheim^J discovered the ex- 
istence of distinct chambers and valves, with lateral orifices in the dorsal vessel of 
insects, all which had been overlooked by Treviranus in the Arachnida, but he was 
unable to discover any vessels connected with, or proceeding from, the dorsal vessel 
in insects. In the Myriapoda, he found the anterior portion of this structure in the 
Scolopendra divided into three branches, which are distributed to the head, and that 
the middle one of these gave off other branches, the course of which he was unable 
to trace. In 1828 Carus published his discovery of a circulation in insects; and 
Wagner in 1832, Mr. Bowerbank in 1S33**, and Mr. TYRREL'f-'f- in 1835, added 
some new facts. But our own countryman Hunter, long before this period, seems to 
have been acquainted with the course of the circulatory fluids in insects, and with the 
existence of the lateral canals described by Wagner, which he regarded as veins. 
Professor Muller^ also, in 1824 had traced a connexion between the dorsal vessel 
of insects and the ovaries, which he described as vascular, although that opinion was 
controverted by Carus, Treviranus, Burmeister and Wagner. Some unpublished 
observations made by myself in 1829 §§ on these structures, several years before I 
was acquainted with the observations of Muller, led me also to regard them as 
vascular, and this opinion has since been strengthened by my recent discovery of 
* Traite Anatomique de la Chenille qui range le bois du Saule. A la Haye, 1760, p. 427. 
f Der Arachniden, 1812; and Vermischte Schriften Anatomischen und Physiologischen inhalts. Gottingen, 
1816 (Die Spinne), p. 5. 
+ Op. cit. (Die Afterspinne), p. 32. § Cours d’Entomologie, &c. 8vo. Paris, 1831, p. 170-176. 
|| Op. cit. Bremen 1817 (Die Scolopender), p. 31. 
Considerations Generates sur l’Anatomie comparee des Animaux Articules. 4to. Paris, 1828. 
** Entomological Magazine, vol. i. April 1833. 
-j-t Proceedings of the Royal Society for January 15, 1835. ++ Nova Acta Nat. xii. 2. 
§§ Cyclopsedia of Practical and Comparative Anatomy, Article “ Insecta,” vol. ii. No. 18. p. 979, Oct. 1839. 
See also Dr. Roget’s Bridgewater Treatise, vol. ii. p. 245, 1834. 
