Moreover, some researches of Otto Folin and W. Denis into _urea formation_ seem to indicate that the older views call for revision. Experimenting on cats, they injected them with _alanine_ and _glycocoll nitrogen_ and other amino-acids as well as Witte’s _peptone_. They were able to prove definitely that, at the end of an hour or more, the formation of _urea_ from the absorbed amino-acids was unmistakably demonstrable. Also they noted that interesting fact, that the “_urea nitrogen_ obtained from the _hepatic blood_ is not larger than the urea in the blood obtained at about the same time from the _iliac artery_.” This they claim indicates that “_the liver has not brought about any demonstrable specialised deaminisation_.” The experimental data forthcoming in their researches, while they prove that the absorption of _amino-acids_ is very swiftly followed by the formation of urea, does not afford any definite evidence as to the _site_ of urea formation; but, as they rightly contend, we have no satisfactory proof that _deaminisation_ and _urea formation_ is _localised_. Consequently “we are not justified in assuming that the process is a specialised process in the sense of being confined to some particular organ.” Indeed, they bring forward evidence that the process of urea formation, far from being localised to any particular organ, _i.e._, the liver, is almost ubiquitous. Thus, experimenting with the injection of _alanine_, they noted that prior to the same the muscle content of _non-protein nitrogen_ and _urea nitrogen_ was respectively 194 and 26 mg.; but 180 minutes after the injection the non-protein content in muscle had risen to 232 and that of urea nitrogen to 41 mg. Working with _glycocoll_, the non-protein and urea nitrogen in muscle before injection of the same was 248 and 42 mg. respectively, while 240 minutes after injection the figures were 304 and 54 mg. The significance of these figures is more striking when contrasted with the fact that in the same subjects the urea nitrogen content of the _hepatic_ blood did not exceed that obtained almost simultaneously from the _iliac_ artery. The deduction made by Folin and Denis is that— (1) “_The urea-forming process is one characteristic of all the tissues, and by far the greatest amount of the urea is, therefore, probably formed in the muscles._” (2) “_The negative results, so far as any localised urea formation is concerned, is almost satisfactory proof that there is none, for if there were one central focus from which all or nearly all of the urea originated we could scarcely fail to find it._” AMINO-ACIDS IN RELATION TO GOUT