INDIGESTION AND NERVOUS DEPRESSION. 235 



is of the highest importance for the nutriment of the body. Under 

 ordinary circumstances, nearly the whole of the sugar formed in the 

 intestine and absorbed from it is arrested in the liver, so that very 

 little passes into the general circulation and appears in the urine, 

 although even in healthy persons traces of sugar are excreted by the 

 kidneys. Under exceptional circumstances, however, sugar may pass 

 through in considerable quantities, as, for example, when the individual 

 takes, on an empty stomach, a large quantity of sirup. However 

 healthy his organs may be, sugar will then appear in the urine. The 

 same is the case in regard to albumen. Usually, the whole albumi- 

 nous constituents of our food are so transformed in the stomach, intes- 

 tines, and liver, that no albuminous substances of the kind which can 

 pass through the kidneys get into the general circulation. But, if one 

 takes such a quantity of eggs as to completely overtask the digestive 

 powers, the egg-albumen will pass unchanged into the blood, and be 

 excreted by the kidneys. 



Other albuminous substances, the products of intestinal digestion, 

 and peptones also, occasionally make their appearance in the urine, as 

 well as egg-albumen. Even when the processes of assimilation are 

 not so seriously interfered with as in these instances, we observe that 

 products of nitrogenous waste frequently occur in the form of lithates 

 in the urine. An excess of these indicates some pathological condi- 

 tion, even although it may be very trivial. We can not, indeed, say 

 what the exact condition is, because we find lithates appearing in the 

 urine after violent muscular exertion accompanied by profuse sweat- 

 ing, so that they may possibly represent some of the products of mus- 

 cular waste ; but we also find that they occur in large quantities in 

 the urine after slight indiscretions in diet, although no muscular exer- 

 tion has been undergone, and in these cases we can hardly do other- 

 wise than regard them as products of the imperfect assimilation of 

 nitrogenous matters which ought to have been eliminated, not in the 

 form of urates, but of urea. Now, physiological experiments and ob- 

 servations indicate that the liver is the chief if not the only part of 

 the body in which urea is formed. This at least appears to be the 

 case excepting in febrile conditions, in which, possibly, the urea may 

 also be formed, to a considerable extent, in the muscles. The old 

 notion, then, which connected the appearance of lithates in the urine 

 with disordered function of the liver, is probably in a great measure 

 correct. There is little or no reason to believe that these lithates are 

 formed in the kidneys. They are, probably, simply separated by them 

 from the blood, and their presence in the urine would therefore indi- 

 cate their presence in the blood and tissues. Now, lithates in them- 

 selves do not appear to have any particularly injurious effects, either 

 upon the nervous tissues or the muscles, but, as their presence indi- 

 cates deficient assimilation, they may be accompanied by other sub- 

 stances which have a much more pernicious action, just as there are 



