560 PHILOSOPHICAL TRANSACTIONS. [aNNO 1733. 



in a great measure of its grosser, saline, oleaginous, and pungent parts, by the 

 filtration, and so lose the power of a stimulus on the inside; as the situation of 

 the parts, and disposition of the nerves above described, made it an ineffectual 

 one on the outside, as much as if it had been carried quite out of the body. 



To conclude, if the gall spilt on the outside of the guts, had been capable of 

 exciting a contraction in any part of them, as soon as it came to cover the 

 whole surface, it must have had the same effect equally every where, and the 

 whole canal should have been found contracted to its smallest diameter: where- 

 as it was found every where distended to a great pitch. 



It is therefore plain, that a stimulus on the outside of the intestines, has not 

 the effect of such a stimulus on the inside. It can neither excite them to a 

 contraction; nor promote their peristaltic motion; nor supply the defect or 

 want of such a stimulus on the inside ; much less occasion such a universal 

 distention, or account for the symptoms arising from it, which is what the 

 Doctor undertook to prove. 



The 2d difficulty is, how a fresh recruit of chyle should be a cause of sleep. 



The exptriments mentioned in Transact. N*^ 'll-i, the Doctor considers may 

 serve to justify what he here assumes, concerning the nature and existence of 

 the nervous fluid, or animal spirits, in the solution of this second difliculty. 

 The argument which has been offered, runs thus : it is well known that people 

 after eating plentifully, are often inclined to sleep, long before the chyle can 

 be supposed to be got into the blood ; therefore a fresh recruit of chyle cannot 

 be the cause of sleep ; but there must be some other cause, at least at that 

 time. Which cause is assigned by supposing, that after a plentiful meal, the 

 distended stomach will load and oppress the descending aorta, so as to hinder 

 the blood in its descent, and so force a greater quantity than usual into the 

 aorta ascendens, which, by its distended branches in the brain, will obstruct 

 the secretion of the animal spirits through the glands of the cortical substance 

 into the origin of the nerves, and thus produce sleep. 



This being generally esteemed a mechanical account of the cause of sleep 

 after meals, deserves the greater attention. In answer to which, if such was 

 the true cause of sleep after meals, it ought to have the same effect on the 

 cerebellum, from whence most of the nerves, that serve in the natural and vital 

 functions, arise; and so would hinder these functions, viz. digestion, the 

 peristaltic motion, respiration, and the circulation of the blood, all which, on 

 the contrary, are observed to be more regular and stronger in sleep, than when 

 we are awake ; at least in a healthy and temperate person, who has used mode- 

 rate exercise. 



Again, gluttony, drunkeimess, and flatuses, which overload the stomach, 



