LETTERS TO BROTHER JOHN. 209 



of the nervous system that are to be attributed all 

 those oppressive feelings of lassitude, ennui, mental 

 imbecility, &c., so prominently characteristic of the 

 hypochondriacal dyspeptic. 



Then we have, too, congestion in the lungs, in- 

 terfering with those important changes which should 

 be effected on the blood in those viscera. 



Then we have congestion in the stomach. In 

 this viscus the food is destined to undergo the first 

 important change towards final assimilation; that 

 is, nutrition. This change is effected by admixture 

 with the gastric juice. The gastric juice is se- 

 creted ; that is, separated from the blood that is, 

 formed or manufactured, as it were, by the arteries 

 entering into the composition of the elementary 

 structure of that organ. But, in order that this 

 juice may be secreted in sufficient quantity, it is 

 necessary that the elementary tissue of its blood- 

 vessels should be plentifully supplied with pure 

 arterial blood : whereas, in congestion, this tissue, 

 as I have before shewn, is gorged with venous 

 blood. The necessary quantity of gastric juice, 

 therefore, cannot be formed; and that portion 

 which is secreted is not of a healthy sort. The 

 direct result of all this is, that the very first neces- 

 sary change which should be wrought upon the 



