FUNCTIONS OF ANIMAL LIFE. 233 



upon its bodily structure, and the power of spontaneously exciting contrac- 

 tions in its tissues, by which evident motions are produced, have been already 

 stated to be the peculiar attributes of the beings composing the Animal king- 

 dom. The evident motions exhibited by some Plants, cannot be regarded as 

 indicating the existence of any psychical endowments in the beings included 

 in the Vegetable kingdom ; for they are usually to be referred without difficulty 

 to the action, either direct or indirect, of an external stimulus, upon a contrac- 

 tile tissue ; and even where no such action evidently takes place, there is good 

 reason to suppose its existence. To refer, therefore, the movements of Vege- 

 tables to a Nervous system, of which no traces can be found, still more to 

 suppose them endowed with consciousness and will, as some have done, is 

 to violate most grossly a well-known rule in philosophy, which cannot be too 

 steadily kept in view in prosecuting physiological inquiries nonjingerc hy- 

 potheses. 



284. There are in Animals, however, many movements which are equally 

 dependent upon direct stimuli for their production ; such are (as we have 

 seen), even in the highest, the actions of the heart and of the alimentary canal. 

 These, in the lowest tribes, probably bear a much greater proportion to the 

 whole amount of those exhibited by the beings, than they do in the higher; 

 whilst those, which we may regard as specially dependent on a nervous sys- 

 tem, appear to constitute but a small part of their general vital actions. The 

 life of such beings, therefore, bears a much closer resemblance to that of the 

 Vegetable, than to that of the higher Animal. Their organic functions are 

 performed with scarcely more of sensible movement, than is seen in plants ; 

 and of the motions which they do exhibit (nearly all of them immediately 

 concerned in the maintenance of the organic functions), it is probable that 

 many are the result of the simple contractility of their tissues, called into 

 action by the stimuli directly applied to them. It is scarcely possible to ima- 

 gine that such beings can enjoy any of those higher mental powers, which 

 Man recognizes by observation on himself, and of which he discerns the ma- 

 nifestations in those tribes, which, from their nearer relation to himself, he 

 regards as more elevated in the scale of existence. If we direct our attention 

 on the other hand, to the psychical* operations of Man, as forming part ot 

 his general vital actions, we perceive that the proportion is completely re- 

 versed. So far from his organic life exhibiting a predominance, it appears 

 entirely subordinate to his animal functions, and seems destined only to afford 

 the conditions for their performance. If we could imagine his nervous and 

 muscular systems to be isolated from the remainder of his corporeal structure, 

 and endowed in themselves with the power of retaining their integrity and 

 activity, we should have all that is essential to our idea of Man. But, as at 

 present constituted, these organs are dependent, for the maintenance of their 

 integrity and functional activity, upon the nutritive apparatus ; and the whole 

 object of the latter appears to be the supply of those conditions, which are 

 necessary to the exercise of the peculiarly animal functions. That his men- 

 tal activity should be thus made dependent upon the due supply of his bodily 

 wants, is a part of the general scheme of his probationary existence ; and the 

 first excitement of his intellectual powers is in a great degree dependent upon 

 this arrangement. 



285. The most simple or elementary function of the Nervous System is, as 

 already observed, the establishment of a communication between a part which 

 is susceptible of impressions, and another which can perform contractile move- 



* Here and elsewhere this terra will be employed in its most extended sense, to designate 

 all the mental operations, whether intellectual, emotional or instinctive, of which Man's 

 nervous system is the instrument. 



20* 



