118 



REPORT ON ZOOLOGY, MDCCCXLIII. 



direct connexion with the brain aiid other nerves. Their function, conse- 

 quently, must be considered reflex. In the same light are to be viewed 

 the nervous filaments, situated on the external side of the cord, and 

 which have no connexion with the brain (strengthening filaments). He 

 accordingly distinguishes four sets of nervons fibres in the abdominal me- 

 dullary cord : (1) niotory, (2) sensitive nerves, both continuous to the 

 brain, the one set forming ganglia, the other presenting none ; (3) the con- 

 necting fibres; (4) the strengthening fibres, both unconnected with the 

 brain, the former being the agents of the reflex function in the transverse, 

 the latter in the longitudinal direction. 



The author has considerably enlarged his discoveries with respect to the 

 vascular system in the Myriapoda and Scorpions. (Vide Report for 1841, 

 p. 193.) He has siicceeded in proving the existence of a completely closed 

 vascular system. In the first place, a minute artery (systemic artery) arises 

 on each side of each chamber of the dorsal vessel, and passes to the sides of 

 the body. The aorta afterwards ramifies in the head, in such a way that 

 arterial trunks proceed to every organ ; but besides these, a vascular circle 

 is formed around the oesophagus, inasmuch as two branches descending on the 

 sides of it unite, in order to form a large vessel (supraspiual artery), which 

 lies upon the upper side of the chain of ganglia ; anterior to each ganglion, on 

 either side a branch is given off, which divides into as many lesser branches 

 as there are nervous filaments proceeding from the ganglion, and which 

 they accompany to the organs. A similar division of the artery occurs at the 

 last ganglion, into branches corresponding with the nerves proceeding from it. 

 In the Scorpion a venous trunk has been demonstrated on the inferior surface 

 of the chain of ganglia. From this, branches proceed to the pulmonary sacs, 

 whence the blood, having been collected into the sinus, is again distributed 

 to the body, in order to be returned to the heart. In the young (larval) 

 condition of the animal, the vascular system is, however, less developed. 



Lassaigne (Comptes rend., Fror. N. Notiz. vol. xxvii, p. 7) 

 has given a report on Iris chemical researches into the 

 tegtimental coverings of the Insecta. A substance peculiar 

 to them, which Odier had already described as Chitine, he 

 would rather have named Entomademm. It is peculiar to 

 the Insecta in the wider sense of the term, occurring 

 in the Spiders as well, whilst it is wanting in the Annelids 

 (earthworm, &c.) 



In the compound eyes, "Will has discovered (Mull. Arch. 

 p. 349) an arrangement of minute filaments, 



thick, which extend from the common expansion of the optic 



