484 7 lie presence of Urea in the Blood of* Birds, fyc. [May 18, 



being examined, urea was crystallised out from it. Search was then 

 made for uric acid, but no trace of this substance was discovered, and 

 yet the renal secretion consisted of urate of ammonium. 



It has been often said that the reason why uric acid is not found 

 in the blood in any appreciable quantities is owing to the rapidity of 

 its excretion by the kidneys, but this statement should certainly 

 apply to urea, which, as I have shown above, is always found in the 

 blood. 



The existence of uric acid in the blood may be looked upon, there- 

 fore, as a morbid phenomenon. With birds, and especially those 

 kept for domestic purposes, as, for instance, caged birds or ducks, 

 the water they drink is frequently strongly impregnated with 

 soluble urate, and this, when taken into the alimentary canal, is 

 absorbed into the blood. I was enabled to crystallise uric acid out 

 of the water of a duck pond, as I stated in a paper read before this 

 Society in 1886. On the other hand, I have examined the blood of 

 many ducks without being able to detect a trace of uric acid. 



In the human subject, in which the average quantity of uric acid 

 found per diem is small compared with the formation of urea, the 

 blood appears, nevertheless, to be frequently contaminated by its 

 presence, not, however, in the form of urate of ammonium, in which 

 it is doubtless thrown out by the kidneys, but in the form of biurate 

 of sodium, in which shape it exists also in morbid deposits — the 

 so-called chalk-stones of medical authors. 



When uric acid is not introduced into the blood by the alimentary 

 canal, its presence must, according to my view, be accounted for by 

 its absorption into the blood from the kidneys after its formation in 

 these organs, and the salt is necessarily changed by the blood from 

 urate of ammonium to biurate of sodium ; whereas, according to the 

 old view, it had to be assumed that urate of sodium was converted 

 into some superurate of ammonium, which I believe all chemists 

 would regard as an impossibility. 



In conclusion, I may remark that the facts and deductions brought 

 forward in this paper must prove, if established, not only of interest 

 to the physiologist, but must aid the pathologist in the investigation 

 of several diseases and be of value in devising methods for their 

 treatment. 



The Society adjourned over the Whitsuntide Recess to Thursday, 

 June 1. 



