163 REPORT — 1866. 



in wliich volition is cut off from its nervous associations. Ey the state of 

 mental activity, I mean simply the waking state of an animal, in contradi- 

 stinction to the condition which obtains dming profound sleep, fainting, or 

 complete etherization. 



During the waking state the muscular sj'stcm of an animal is maintained, 

 through the medium of the nervous, in a condition of slight contraction, in 

 which the muscles firmly balance or steady each other, and thus the will 

 holds firm possession of the muscular organism. It would appear that this 

 active volitional state involves a constant expenditure of neuro -muscular 

 force. In profound sleep and allied conditions this psycho-neui-al influence 

 ceases to operate upon the muscular system ; hence we find the head falls 

 forward upon the chest, the arms sink down, the fingers relax ; if the person 

 is standing he may fall down, or if sitting slide from his chair ; the eyes 

 become closed, &c. 



In fainting and death the same powerless, flaccid condition of the muscular 

 system is seen in excess ; yet in all these cases the elasticity and irritability 

 of the muscular system still exist. 



Sleep, fainting, deep etherization, and death seem to represent different 

 degrees of what may be called functional neural paralysis, in contradistinc- 

 tion to purely muscular, iu which the irritability of the muscular tissue is 

 diminished or gone, while the nexirUity of the nervous centres and nerves 

 remains. 



When we reflect that the mere waking state of animals involves a con- 

 stant expenditure of both nervous and muscular force, the importance of 

 sleep for their reaccumulation becomes obvious. It is not, therefore, alone 

 in the production of motion that the will consumes ueuro-muscular force, 

 but also in the maintenance of the normal position of the animal ; for few 

 muscles of the body are during the waking state iu a condition of non-con- 

 trol or laxity; most are subjected to continuous stimulation of a mild form. 

 In the tremulousness of old age, or after exhausting disease, we mtness the 

 effect of deficiency of this tonic power. 



Whenever the mind has to make a greater effort than usual for the accom- 

 plishment of an act, it is an evidence that the forces of the sj^stem are below 

 par, and do not respond with their accustomed delicacy to the influence or 

 stimulus of the Avill ; in such cases the animal is said in common parlance to 

 be tired or fatigued. 



The degree of stimulation exercised by nerve upon muscle may be normal 

 or abnormal ; and in proportion to the severity of the stimulation will be 

 the rapidity ^vith which irritability -nail be cojisumed and rigor mortis 

 supervene. 



There appear to be three conditions of nerve in resjiect to the muscular 

 tissue : — 



1. It may exist as a mere structure, i. e. functionally inactive. 



2. It may be in that condition vrhich enables an animal so to control its 

 limbs as to maintain any required position. 



3. It may be concerned in producing actual movement. 



The two latter conditions appear to be degrees of the same kind of action. 



We wish to ascertain by dii'cct experiment whetiier all or any of these 

 conditions of nerve are concerned in exhausting muscular irritability. 



This is by no means an easy matter ; for although we have abundance of 

 experimental evidence from the negative stand-point, that u-ritability is ex- 

 alted, in the ahsence of nerve-influence, it is difficult to devise reliable experi- 

 ments in siipport of the positive proposition. The reasons of this wiU become 



