688 THE SEAT OF FORMATION OF UREA 



by experiment. That ammonia does act as a base in an acid 

 intoxication seems to be shown by the fact that its excretion 

 can be very greatly reduced by putting into the animal's body 

 a sufficient quantity of some other base. But that ammonia 

 is specially produced either in health or disease with the object of 

 neutralising acid is open to question. For the view implies 

 that the quantity of ammonia produced is determined by the 

 amount of acids formed and the quantity of other available 

 base which can be spared by the body. The evidence on this 

 point is not sufficient to enable us to form a decided opinion, 

 but so far as it goes it is against this view. If we take the 

 percentage of ammonia in the blood as the only rough guide 

 we have to the amount produced, then it is not found that the 

 quantity of ammonia formed bears any necessary relation 

 to the degree of acid intoxication. Salaskin and Zaleski found 

 in their experiments that a dog might be in convulsions and 

 passing lactic acid in its urine, and yet the percentage of 

 ammonia in the blood and tissues be normal. The same thing 

 has been noticed in cases of severe diabetes. The abnormality 

 in an acidosis appears to be, not in the quantity of ammonia 

 formed, but in the degree to which the ammonia is converted 

 into urea. When in addition to an acidosis there is destruction 

 of the liver, it is obvious that the conversion of ammonia into 

 urea may almost cease. The relation of the liver to acidosis 

 may, therefore, be twofold : on the one hand, destruction or 

 gross impairment of the liver interferes with the oxidation 

 in the liver of lactic and possibly other acids, and an acid in- 

 toxication results. On the other hand, when an acid intoxica- 

 tion has arisen from some cause not primarily connected with the 

 liver, the conversion of ammonia into urea by the liver is sus- 

 pended in a degree corresponding to the acidosis, necessary 

 base is thereby obtained, and a corresponding proportion of 

 the total N in the urine appears as ammonia instead of urea. 

 Even in health something less than about 5 per cent, of the total 

 N is excreted as ammonia. But the whole of this cannot be 

 looked upon as being present only because it is required as 

 a base. For, if a healthy man is given sufficient sodium 

 bicarbonate by the mouth to make his urine for days strongly 

 alkaline, the ammonia in it does not disappear, it is only greatly 

 reduced. The ammonia now present cannot be looked upon 



