132 PHYSIOLOGY. 



same persons who otherwise would be vomited with one grain 

 of tartar emetic, will now perhaps require ten to produce the 

 same operation ; and one that might have been laid asleep with 

 half a grain of opium, will now take five. They will also sometimes 

 resist the force of all impressions. There are maniacs, indeed, who 

 have an increased sensibility with regard to particular organs, 

 but the opposite is commonly the case. What connexion there is 

 between the diminution of sensibility and the increase of strength, 

 may be difficult to explain ; it is difficult in theory, and I do not 

 attempt it, but the combination is frequent, and we say that it 

 is analogous to the state of elastic chords : the more they are ex- 

 tended the greater is their force of contraction ; at the same 

 time, they are nearer breaking ; and you will find somewhat 

 analogous to this in the degree of density and elasticity of 

 elastic fluids. Thus, in compressing the air, double the weight 

 does not give double the compression ; but it is in proportion to 

 the degree of condensation, that the elastic power will show its 

 force, and operate upon the body that is compressing it in order 

 to remove it." 



CXXXII. A lesser degree of excitement occurs in the or- 

 dinary state of waking men in health, when the excitement 

 is total with respect to the functions of the brain, but readily 

 admitting of sleep. " I have been a little at a loss in the ap- 

 plication of the terms of excitement and collapse. There is no- 

 thing more manifest than that the degree of excitement is very dif- 

 ferent upon different occasions; and if we take the lowest, every 

 higher degree than that must be called a degree of excitement; and 

 if we take the highest degree, and consider the lower degrees that 

 may take place while life still subsists, every lower may be call- 

 ed a degree of collapse ; so the same ambiguity occurs here as 

 with regard to the terms of heat and cold, which may be absolutely 

 applied to the same individual state of bodies. Philosophers 

 have not yet agreed where they should begin with applying the 

 terms heat and cold, and so it may be with regard to the terms 

 excitement and collapse; but I mean by this to settle the 

 matter a little more exactly, and I would call those states, 

 states of excitement, where the excitement is total with regard 

 to the functions of the brain, where there is in every part the 

 general exercise of sense and volition ; I know that there are 



