206 



such as snuff or ammonia ; yet the sense of smelling continued un- 

 impaired. The left side of the tongue was quite insensible to im- 

 pressions both of touch and of taste. On examining the brain after 

 death, a scirrhous tumour was found lying on the inner surface of the 

 sphenoid bone, extending laterally to the foramen auditorium inter- 

 num, and resting posteriorly on the pons Varolii, which was slightly 

 ulcerated. The tumour had completely obliterated the foramina for 

 the exit of the three branches of the fifth pair of nerves. This case 

 proves, therefore, that, contrary to the opinion of Magendie, the senses 

 of smell and vision can be exercised independently of the fifth pair of 

 nerves j and that the sense of taste is altogether derived from that 

 nerve ; and corroborates the views of Sir Charles Bell on this part of 

 physiology. 



2. " On the Respiratory Organs of the Common Leech (Hirudo offi- 

 cinalis, Linn.), and their Connexions with the Circulatory System." 

 By George Newport, Esq. Communicated by P. M. Roget, M.D., 

 Sec. R.S. 



The stomach of the leech has been hitherto described as a large 

 elongated sac, simply divided into ten compartments by perforated 

 membranous partitions : but the author, by a more accurate exami- 

 nation, finds that each portion of that organ is expanded into two 

 lateral caeca, which increase both in size and in length as they are 

 traced along the canal towards the pylorus. The caeca belonging to 

 the tenth cavity are the longest, extending as far as the anus, and 

 have themselves four constrictions : the cavity itself terminates in a 

 funnel-shaped pylorus. When the posterior end of the animal is cut 

 off, the caecal portions of the stomach are laid open, and the blood 

 which it receives flows out freely, as fast as it is swallowed ; and 

 hence the leech, under these circumstances, continues to suck for an 

 indefinite time. 



The respiratory organs consist of two series of pulmonary sacs, ar- 

 ranged along the under side of the body, on each side of the nervous 

 cords and gangiia. They each open upon the surface of the body by 

 a very minute but distinctly valvular orifice. The membrane which 

 lines them appears to be continuous with the cuticle, and is exceed- 

 ingly delicate and highly vascular, receiving the blood, for the purpose 

 of its being aerated, from the veins of the system. The blood is re- 

 turned from these sacs into the lateral serpentine vessels by vessels 

 of a peculiar construction, passing transversely, and forming loops, 

 which are situated between the caeca of the stomach, and which are 

 studded by an immense number of small rounded bodies closely con- 

 gregated together, and bearing a great resemblance to the structure 

 of the venae cavae of the cephalopodous Mollusca. The purpose an- 

 swered by this structure is involved in much obscurity : the author 

 offers a conjecture that they may be analogous in their office to the 

 mesenteric glands of the higher animals. 



With a view to determine some circumstances relating to the mode 

 of the respiration of the leech, the author made some experiments, by 

 confining the animal in water deprived of air by boiling. After some 



