June 27. 



REV. J. H. TODD, D. D., Vice-President, in the Chair. 



H. J. Monck Mason, Esq., LL.D., read an account of 

 a visit which he had paid to the Tomb of the Volumnii at 

 Perugia. 



Mr. Mason then presented a gold fibula found in Ireland, 

 as a contribution to the Museum of Antiquities, now in pro- 

 cess of formation by the Academy. 



The thanks of the Academy were voted to Mr. Mason for 

 the donation. 



A paper was read by Dr. Macartney " on the minute 

 Structure of the Brain in the Chimpanzee and the human 

 Idiot, compared with that of the perfect Brain of Man, with 

 some reflections on the Cerebral Functions." 



The author commenced by stating, that he had disco- 

 vered the brain of all animals to be composed of a plexiform 

 arrangement of white (or, as he termed them, sentient) fila- 

 ments, the most delicate of which he found to pervade all the 

 coloured substances of the brain. He attributed the higher 

 sensorial powers of the cerebral organ to the disposition and 

 intercommunication of these filaments, more especially where 

 they exist in the coloured substances. The mode he em- 

 ploys for rendering the finer filaments evident is to moisten 

 the different substances during the dissection with a solution 

 of alum in water, which, causing a slight coagulation, makes 

 the filaments opaque and visible. The author accounted for 

 the fact that the existence of the most delicate plexuses had 

 hitherto escaped observation, from the circumstance that 

 other anatomists had not used any fluid to coagulate them. 

 He considers the shape and magnitude of the different parts 

 of the brain as merely subservient to the proper arrange- 

 ment and number of the plexuses of the sentient substance. 



