INDIGESTION AND NERVOUS DEPRESSION. 377 



more thoroughly than it has been up to the present, it is just possible 

 that we may by and by find that the digestive ferments, like all other 

 powerful agents, may do much harm as well as much good. Hitherto 

 we have been accustomed to regard the phases of digestion, gastric 

 digestion, pancreatic digestion, and intestinal digestion, as almost sepa- 

 rate processes, any of which we might increase indefinitely without 

 doing any harm to the jsatient. We forget the relation which each 

 bears to the other ; and yet such a relation undoubtedly exists, for we 

 find that when pepsin is mixed with bile it is precipitated and ren- 

 dered inert. Further transformation of foods by the gastric juice is 

 thus arrested as soon as the chyme leaves the stomach. And well it is 

 that this should be so, for if the pepsin were not rendered inert it 

 would destroy that pancreatic ferment (trypsin) which acts on albumin- 

 ous substances, and thus interfere with digestion by it. How far this 

 prolonged peptic digestion and impaired pancreatic digestion of albu- 

 minous substances has to do with the production of poisonous diges- 

 tive products in cases where the quantity of bile poured into the intes- 

 tine is deficient it is at present impossible to say, but it is a condition 

 which ought to be kept in mind in all cases where there is deficiency 

 of bile in the intestine, and the advisability of nourishing the patient 

 by farinaceous food is constantly considered in these cases. 



And now comes the question, How is it that in healthy conditions 

 of the intestine peptones do not pass into the general circulation, and 

 are therefore unable to exert any poisonous action upon the nerve-cen- 

 ters ? This question is one which we can not at present answer quite 

 satisfactorily. 



Usually the peptones disappear from the portal blood before it 

 reaches the general circulation. Indeed, Ludwig and Schmidt-Miihl- 

 heim found that even in the portal blood, before it reaches the liver, 

 very little if any peptone is to be found. They have not succeeded in 

 discovering where the peptone undergoes change. Plosz and Gergyai, 

 and also Drosdorff, have discovered peptone in the blood of the portal 

 vein, and Plosz and Gergyai have been led, by their experiments, to 

 regard the liver as the seat of the transformation of peptones. In con- 

 sideration of the more recent experiments of Ludwig and Schmidt- 

 Miihlheim, we can not entirely adopt the view of these authors, though 

 it is nevertheless possible that they are to a certain extent right, and 

 that the liver, to some extent at least, serves the purpose of preventing 

 any peptones from getting into the general circulation, which may 

 have escaped transformation in the portal blood before reaching it.* 



And now, having run over in this cursory manner some points con- 

 nected with digestion and with the functions of the liver, we come 

 back to the question of why it is that the mental worker becomes de- 



*Schmidt-Muhlheim, "Archiv fiir Anatomie und Physiologie ; physiologische Abth.," 

 1. & 2. Heft, 1S80, p. 33. Albertoni, " Ceiitralblatt f. d. medicinischen Wissenschaften," 

 1880, p. 577. 



