60 NERVOUS SYSTEM. 



of sight (Talpa Asiatica, some of the Ophidio-Batrachians, 

 Myxine) ; Serres also considered these as centres for co-ordi- 

 nation of movements ; the explanation of this seems to be 

 in the fact that these tubercles have some relation to excito- 

 motory impulsions, which would authorize their classification 

 with the cerebral centres, as a medium between the protu- 

 berance and the clusters of cerebral and cerebellar cells (see 

 p. 33, fig. 12). 



The functions of the cerebellum are a problem diflicult of 

 solution ; experimentation and observation from pathological 

 conditions give us but negative and contradictory results ; 

 ablation of the cerebellum shows that this large portion of the 

 encephalon takes no part in the intellectual functions, strictly 

 speaking, nor in the manifestations of sensation, memory, 

 instinct, or volition. Its peculiar functions are so difficult to 

 define that almost all possible opinions have been proposed. 

 Leaving out of consideration the opinion of Willis, who, at 

 the time when the theory of the animal spirits held sway, 

 made it the point of departure for the innervation of organic 

 functions, we notice that some physiologists (Lapeyronie, 

 Pourfour du Petit, Duges), basing their opinion upon the 

 apparent continuity of the inferior cerebellar peduncles with 

 the posterior columns of the spinal cord (conductors of sen- 

 sation or sensibility), considered the cerebellum as the central 

 organ of sensibility, the sensorium commune to which all the 

 peripheral sensations pass for elaboration and arrangement, 

 especially including the auditory (Foville) and visual sensa- 

 tions (Lussana). We have already noticed that this role of 

 the centre of sensation belongs in part to the protuberance 

 and in part to the tubercula quadrigemina. With less rea- 

 son, but perhaps more fortunate in his hypothesis, Gall con- 

 sidered the cerebellum as a centre of animal love, or erotic 

 passion / indeed, in spite of the experiments and contradic- 

 tory observations by Leuret, Segalas, Combette, and Vulpian, 

 we notice several reasons brought out by experimentation 

 and clinical observation by Budge, Valentin, Wagner, Lus- 

 sana, which would seem to give some appearance of reality 

 to the hypothesis of Gall, and to assign an important func- 

 tion to the middle lobe in the manifestations of genital in- 

 stinct. 



The cerebellum, however, seems to have an important part 

 in the apparatus for the co-ordination of movements as ap- 

 pears from the experiments of Rolando, and especially from 

 the more recent and numerous experiments of Flourens ; in the 



