224 THE URINE. 



Under normal conditions it is assumed that the lactate is trans- 

 formed into ammonium carbonate, which in turn yields the carba- 

 mate, and the urea finally results through a synthetic process, which 

 is probably effected through the agency of a certain ferment. We 

 may further imagine that the paralactic acid in the last instance may 

 result from a decomposition of the mono-amido-radicles of the albu- 

 minous molecules, and in this form the theory would embrace the 

 two outlined above. The various changes may be represented by 

 the equations : 



(1) 2NH 4 .C 3 H 5 3 + 120 = (NH 4 ) 2 C0 3 + 5CO 2 + 5H 2 O 

 Ammonium lactate. 



(2) (NH,) 2 C0 3 = CO/ + H 2 



X).NH 4 



Ammonium 

 carbamate. 



NH 2 NH 2 



(3) CO/ ^ = CO/ ^ + H 2 



Urea. 2 



While we have seen that urea may originate in the animal body 

 through a process of oxidation only, as also synthetically through 

 alternate reductions and oxidations, there is still another possibility, 

 viz., that it may be derived from the albumins by hydrolysis only. 

 We know, as a matter of fact, that a number of nitrogenous substances 

 are found in the body, such as kreatin, kreatinin, oxaluric acid, and 

 others, which on hydrolytic decomposition give rise to the formation 

 of urea, and it is quite possible that a certain proportion may be 

 referable to this source. 



We have also seen that on hydrolytic decomposition all albumins 

 which have been examined in this direction yield comparatively 

 large amounts of arginin, and that this can be further decomposed 

 in the same manner into ornithin and guanidin, which latter then 

 yields urea. As arginin is now known to occur in the animal body 

 as such, there is no reason for supposing that a certain fraction of 

 the urea may not be formed as just indicated, and Drechsel indeed 

 has expressed the opinion that 10 per cent, of the total amount may 

 thus result through hydrolytic processes only. 



Hoppe-Seyler has suggested that in the transformation of the 

 mono-amido acids into urea cyanic acid may be produced as an inter- 

 mediary product, and that urea then results through the interaction 

 of two molecules of this acid, as is shown in the equation : 



CONH + CONH + H 2 O = CO/ * + CO 2 . 



X NH 2 



In all probability a certain amount of urea is produced in the 

 animal body in different ways, and there is reason to believe, more- 

 over, that its formation is not confined to one single organ. The 

 greater portion, no doubt, is formed synthetically in the liver. Of 



