225 



remarkable circumstance suggests the following question. Is this 

 behaviour common also to the corresponding compounds of arsenic, 

 phosphorus and nitrogen, and can the position of each of the five 

 atoms with which these elements respectively combine be occupied 

 indifferently by an electro-negative or an electro-positive element ? 

 This question, so important for the advance of our knowledge of 

 the organic bases and their congeners, cannot now long remain 

 unanswered. 



5. "On the Dentate Body of the Cerebellum/' By William 

 Brinton, M.D. Communicated by R. B. Todd, M.D., F.R.S. &c. 



Received May 23, 1852. 



The corpus dentatum has generally been described and recognised 

 as a wavy line or lamina of grey matter, which is seen in certain 

 sections of the crus of the cerebellum, and contains fibres apparently 

 derived from the restiform body, and the processus e cerebello ad 

 testes. Reil's account, with some vague and conflicting details, gives 

 it a more definitely tubular form, although he is apparently not cer- 

 tain of the continuity of its upper and lower layers posteriorly. 



The author explains these somewhat varying descriptions by the 

 physical characters of the tissues investigated, and by the condition 

 — fresh or hardened in spirit — of the specimens examined by differ- 

 ent anatomists. 



He deduces the form and situation of the recent corpus dentatum 

 by uniting numerous and successive sections made in the three direc- 

 tions of space"^. Its arrangement with respect to the fibres of the 

 cerebellum, cerebrum, medulla oblongata, and medulla spinalis, is 

 chiefly deduced from examinations of specimens hardened in al- 

 cohol. 



By these two methods he is led to the following conclusions, that 

 each corpus dentatum forms a tubular investment to the extremity 

 of the processus e cerebello ad testem ; it is open towards the fourth 

 ventricle, and is connected with the opposite body by a commissure 

 of grey matter in its median line. While its interior exclusively 

 receives the fibres of this cerebro-cerebellar peduncle, its exterior 

 radiates fibres to the various lobes of the cerebellum, which fibres, 

 at the bottom of each lobe-stem, become inseparably mixed with a 

 bundle from the restiform body, and with another from the pons 

 varolii. 



Its comparative anatomy in mammalia corresponds with this view ; 

 its minute anatomy does not contradict it. And while the physiolo- 

 gical import of this arrangement eludes all conjecture, the author has 

 little doubt that its anatomical structure and relations are best com- 

 prehended in the formula which he would thus assign to it, viz. that 

 of being the cerebro-cerebellar gangUon. 



6. " Proof of a sensible difference between the Mercurial and Air- 

 Thermometers from 0° to 100° C." By J. J. Waterston, Esq. 



* Diagrams to this effect accompanied the paper. 



