312 THE CAT. [chap. ix. 



being unable to rise after tliey liave been thrown down if the cere- 

 bellum has been removed. The greatest caution however is needed 

 in concluding from negative facts, and, as yet, it cannot be safely 

 affirmed what is the true and special function of this remarkable 

 organ, the predominant connexions of which are with the spinal 

 cord and not with the brain. 



§ 35. The true functions of the cerebrum are also far from 

 being satisfactorily known. It has been generally regarded as the 

 organ of cognition, and it is abundantly proved that the destruction 

 of both the cerebral hemispheres puts an end to all manifestations 

 of intelligence, so that this view may be to a certain extent accepted. 

 Becent experiments also tend to make the opinion probable, 

 that certain of its surface regions are related to the five special 

 senses. But similar experiments have also shown that the electrical 

 stimulation of different parts of the cerebrum will cause different 

 movements. Such movements, however, may after all be due in 

 fact to the necessarily induced irritation of more deeply seated 

 parts by the unavoidable diffusion of currents. It seems, however, 

 to be fully proved that the cerebrum has a great deal to do with 

 motion, and is an important motor centre. It may be that by its 

 sensory and motor connexions it ministers to that sense of effort, 

 and to those feelings of different kinds and degrees of effort which 

 are often spoken of (perhaps unfortunately) as the " muscular 

 sense," and to feelings of movement. For the present, however, 

 the true functions of the cerebrum cannot be said to be known, 

 although they afford abundant matter for more or less ingenious 

 speculation. 



§ 36. The FUNCTIONS of the sympathetic system relate to the 

 performance of the organic functions of the body, and especially 

 regulate the activities of the viscera. 



On account however of the multifold and intimate connexions 

 of this system Avith the cerebro- spinal system, it has been as yet 

 impossible certainly to determine what activities are truly under 

 the control of the sympathetic. Normally its actions do not give 

 rise to sensation, though in unhealthy conditions pain may accom- 

 pany them. The presence of ganglia and afferent and efferent 

 fibres renders it in the highest degree probable that somp sympa- 

 thetic nervous action is of the reflex order, — complete in itself and 

 more or less independent of the cerebro-spinal system. The action 

 of the sympathetic, by stimulating the secretion of glands, may call 

 into play instinctive actions and stimulate emotions. Both secretion 

 andi nut fit ion are greatly influenced by the sympathetic, but this may 

 be, but indirectly, owing to alteration of the calibre of the arteries by 

 the influence of the vaso-motor nerves. Such of the arteries as are 

 supplied from any particular branch of the sympathetic become 

 dihited when that particular branch is cut. It is supposed that the 

 action of the vaso-motor nerves (derived partly from the sympathetic, 

 partly from the cerebro-spinal system,) is to keep the muscular coats 

 of the arteries moderately contracted, and that, therefore, when the 



