of M. Flourens on the 'Nervous. System. 121 



punctures and wounds may be inflicted without causing pain. 

 Thus M. Flourens punctured the hemispheres, without pro- 

 ducing either contraction in the muscles, or appearance of 

 pain in the animal ; he removed them in successive lamina; ; 

 he perfoi'uied the same operation on the cerebellum ; he took 

 away, at the same time, the hemispheres and the cerebellum. 

 The animal remained impassive. The corpora striata and 

 tlie optic thalami were attacked and removed, without pro- 

 ducing any other effects. The iris was not even contracted in 

 consequence, nor was it subsequently paralysed. But when 

 he punctured the tubercula quadrigemina, trembling and con- 

 vulsions immediately took place, and increased in proportion 

 as he penetrated more deeply into the medulla oblongata. The 

 pricking of these tubercula, or of the optic nerve, produced 

 acute and prolonged contractions of the iris. 



Tliese experiments agree with those of Lorry, printed in tlie 

 third volume of the Memoires des Savans etra?igers. " Neither 

 irritations of the brain," says Lony, " nor of the corpus callo- 

 sum itself, produce convulsions : it may even be removed with 

 impunity. The only part, among those contained in the brain, 

 capable of uniformly and universally exciting convulsions, is 

 the medulla oblongata : it is that part which produces them to 

 "the exclusion of all others," 



These experiments contradict those of Haller and Zinn, in 

 all that regards tlie cerebellum ; but from the observations of 

 M. Flourens, it appears that these physiologLsts had touched 

 the medulla oblongata without perceiving it. Hence M. Flou- 

 rens concludes (to use his peculiar language), that the medulla 

 oblongata and the tubercula are irritable; which in ours signifies 

 that they are, like the spinal marrow and the nerves, conduc- 

 tors of irritation ; but that neither the cerebrum nor the cere- 

 bellum has that property. The author concludes also, that 

 these tubercles form the continuation and the superior termi- 

 nation of the spinal marrow and the medidla oblongata -, and 

 this conclusion is in perfect conformity with their relations 

 and anatomical connexions. 



Wounds of tlie cerebrum and cerebellum produce neither 

 pain nor convulsions ; and, in ordinary language, we should 

 thence pronounce that the cerebrum and cerebellum are insensi- 

 ble. But M. Flourens says, on the contrary, that these are 

 the sensible parts of the nervous system; which only means, 

 that they are tlie parts at which the impression received by the 

 sensible organs must arrive, before the animal can experience 

 a sensation, 



M. Flourens appears to us to have completely proved this 

 proposition, as tiir as regards the senses of sight and hear- 



Vol.tjl. .\'o. 298. Feb. 182S, Q ing. 



