240 LECTURE XI. 



easily go over into uric acid; in fact, when isolated organs are used, this 

 result has been accomplished. Wiener assumes from this that lactic acid: 



CH 3 



CHOH 



COOH 

 goes over into tartronic acid: 



COOH 



CHOH 



COOH 

 which then forms dialuric acid: 



NH-^CO 



io i 



HOH 

 NH CO 



and finally, by the addition of the urea radical, produces uric acid: 



NH CO 

 CO C NH 



I II >co 



NH C NH 



We should, therefore, have to assume that the main cause of the disturb- 

 ance in the synthesis of uric acid, after the liver had been removed, was 

 the non-oxidation of lactic acid into tartronic acid, and, evidently, also, the 

 non-formation of urea. 



It is clear that we are not yet prepared to state that the formation 

 of uric acid proceeds normally in this manner. Wiener's investigations 

 at all events indicate the manner in which the synthesis may proceed. 

 Wiener also advances the opinion that the organisms of human beings 

 and mammals in general synthesize at least a part of their uric acid, and 

 he sees no real difference in principle between their metabolism of albumin 

 and especially in the formation of their end-products from that of birds 

 and reptiles. The distinction is rather a quantitative one. Birds and 

 reptiles likewise produce urea, but the amount formed is less than that of 

 uric acid. On the other hand, urea predominates in human beings and 

 mammalia. It cannot be denied that such an assumption has much to 

 commend it. Nowhere in the animal kingdom do we observe any sharp 

 demarcations, especially in those processes which are of such great impor- 

 tance as is the case with metabolism. The synthetic formation of uric 

 acid among mammals, according to our present knowledge, must, never- 



