THE CEREBELLUM 609 



marked,, or may be present when there is no derangement of the movements. 

 These two symptoms are therefore entirely independent of each other. Ver- 

 tigo is distinguished by its great intensity and is almost continuously per- 

 manent. Sometimes it is present while the patient is lying down, but as a 

 rule only when he sits up. Sometimes it seems to the patient as if the objects 

 all about him were moving, but as a rule he imagines himself to be moving, 

 that everything supporting him has fallen away and that his body assumes 

 all sorts of impossible positions. 



When we have added that the patient often suffers pain in the head, which 

 is commonly localized just above the neck on the same side, we have enumer- 

 ated all the symptoms of a cerebellar lesion, so far as it is recognizable at all 

 by external symptoms. 



Individuals suffering from extensive or complete congenital defect of the 

 cerebellum are observed to be considerably defective in intelligence also. But 

 we cannot conclude from this that the cerebellum is of any direct significance as 

 the seat of the psychical activities, for it is almost self-evident that the causes 

 which operate to inhibit development of the cerebellum would have an inhibiting 

 influence on other parts of the brain. Besides, we find in the literature cases 

 of very extensive destruction of the cerebellum not accompanied by any notice- 

 able effect on the intelligence. 



From these experimental and clinical results Luciani concludes that the 

 cerebellum both histologically and physiologically is a bilateral organ, but that 

 its influence is rather direct than crossed; whereas the influence of the cere- 

 brum, also a bilateral organ, is mainly crossed. While the influence of the 

 cerebellum however is not limited to the muscles active in locomotion, but 

 extends to the entire voluntary musculature, its chief influence is over the 

 muscles of the posterior extremities and the extensor muscles of the spinal 

 column. 



In general all regions of the cerebellum would, in Luciani's view, appear 

 to have the same function, so that the permanent effects of removal of the dif- 

 ferent parts would differ not in kind, but merely in extent, duration and intensity, 

 and also as to predominance on the one side of the body or the other. The cere- 

 bellum therefore would not be a collection of several functionally different parts, 

 each having a direct relation to a special group of muscles ; but on the contrary 

 a functionally homogenous organ, the different parts of which have the same 

 general purpose as the whole and are mutually replaceable so long as their natural 

 connections are not disturbed. 



This conception cannot at present be so definitely maintained, for we have 

 some observations which show pretty positively the presence of a functional 

 localization in individual lobes of the cerebellum. Thus Thomas observes that 

 destruction of the vermis disturbs more especially the movements of the poste- 

 rior extremities; and, according to v. Rynberk, destruction of the middle half 

 of the vermis affects the neck muscles, while sharply circumscribed destruction 

 of that part of the hemisphere just lateral to this middle region affects the 

 movements of the anterior extremity (dog). 



Impulses are conveyed to the cerebellum by many different pathways (Fig. 

 271). We shall consider first of all those which connect with the vestibular 

 nerve and those traversing the lateral cerebellar tract of the cord (cf. Fig. 264 



