358 INNERVATION. [CHAP. XI. 



The intimate connexion of the olivary columns with the gray 

 matter of the cord, and through that with all the roots of the spinal 

 nerves, illustrates the power of emotional changes upon the organic 

 processes. How often does the state of the feelings influence the 

 quantity and quality of the secretions, no doubt through the power 

 of the nerves over the capillary circulation ! Blushing is produced 

 through an affection of the mind, acting primarily on the centre of 

 emotion, and through it on the nerves, which are distributed to the 

 capillary vessels of the skin and the face. 



The sexual passion must be ranked among the mental emotions. 

 Like them, it may be excited and ministered to by a certain line of 

 thought, or by particular physical states of the sexual organs. It 

 seems, therefore, more correct to refer this emotion to the common 

 centre of all, than to a special organ according to GalPs theory; 

 and it may be remarked, that great development of this part of the 

 brain is just as likely to produce great width of cranium in the 

 occipital region as a large cerebellum. 



Of the Functions of the Cerebellum. All anatomists are agreed in 

 admitting, in the whole vertebrate series (the amphioxus excepted), 

 the existence of a portion of the encephalon which is analogous to 

 the cerebellum. This extensive existence of such an organ indicates 

 its great physiological importance, as a special element of the ence- 

 phalon. The cerebellum exhibits much difference both as regards 

 size and complexity of structure in the different classes ; and al- 

 though, upon the whole, it increases in its development in the same 

 ratio as the hemispheric lobes, it exhibits no constant relation of 

 size to those parts. 



The large size and complicated structure of this organ in the 

 higher vertebrate animals, and its distinctness from the other parts 

 of the brain, for its commissural connexions are not extensive, 

 have excited the interest and curiosity of speculative physiologists ; 

 and, accordingly, we find no part respecting which a greater variety 

 of hypotheses have been suggested, most of them being entirely 

 devoid of foundation. The experiments of Flourens have, how- 

 ever, thrown more light on this subject than any previous observa- 

 tions ; and his hypothesis appears to us nearer the truth than any 

 which has been proposed. We shall content ourselves with ex- 

 amining this theory, as well as that of Gall, which assigns the 

 cerebellum as the organ of the sexual instinct. 



The facility with which the cerebellum may be removed or in- 

 jured, especially in birds, without involving the other segments of 

 the brain, renders it a much more favourable object for direct expe- 



