THE NERVOUS SYSTEM. 437 



felt, none is expectorated, and mucous rattle occurs in the trachea. 

 The blood, consequently, is no longer exposed properly to the air. 

 These changes are declared to happen even after death, if the ex- 

 periment is made as soon as the animal is killed ; but I really 

 doubt this. 



Every point of the body communicates with the brain by 

 means of nerves: since, on the one hand, every point of the 

 organisation either is sensible or may by disease acquire sensi- 

 bility and communicate painful sensation to the brain 1 ; and, on 

 the other, mental emotions, continued or violent, may affect any 

 point. We cannot, therefore, be surprised to see nerves pass 

 between the encephalon or spinal chord and parts which ordi- 

 narily have no sensation and are never under the influence of 

 volition. Indeed, many parts considered insensible are at all times 

 destined to give some variety of sensation, under certain circum- 

 stances, without any morbid sensibility. The want of chemical 

 change in the lungs for less than a minute so impedes the passage 

 of blood through them, that we have an uneasy sensation : the 

 stomach feels hunger, and it, and the intestines, and urinary 

 bladder, feel distension every day in health : the ligaments, un- 

 doubtedly, give a peculiar sensation if a joint is over distended : 

 and the testis or coats of the testis when compressed. k The func- 

 tions of the lungs and stomach could not easily proceed without 

 sensation. In the one we feel the want of air, if we interrupt 

 the function, as we continually do when talking and eating and 

 performing many other acts, in all which we are compelled to 

 attend to respiration by an uneasy feeling : without sensation in the 

 stomach, supplies of food would not be given to it and regulated. 

 The necessity for almost continual sensation in the lungs and 

 stomach explains why a nerve goes directly from the brain to these 

 organs, the pneumono-gastric. The end of the intestines and 

 the bladder require habitual sensation for their functions, and they 

 are well supplied from the spinal chord. The functions of the rest 



1 In nervous disturbance, the parts which carry on the organic functions 

 without sensation sometimes acquire such sensibility that the ordinary silent 

 processes appear attended with sensations : at any rate, unusual sensations are 

 felt in such parts. 



k I have compressed the tunica vaginalis and the albuginea when the testis 

 was atrophied after mumps, and great pain was felt. Still, although nothing but 

 membranes appeared left, there probably was a portion of the gland, as pressure 

 of the vas deferens is equally painful. 



G G 4) 



