430 THE METABOLISM OF THE PURIN BODIES 



as a possible source of purins, and very recently Burian has 

 brought forward evidence which places beyond all doubt this 

 muscular derivation, and which indeed would seem to show that 

 most of the endogenous moiety is thus derived. 



Two types of experiment were employed by Burian to study 

 this question. In the one, an estimation of the endogenous 

 purins was made in the urine excreted every hour from 6 A.M. 

 to 2 P.M., during all of which time the person (Burian himself) 

 lay perfectly quiet in bed except for one hour (9-10), when 

 strenuous muscular exercise was practised. For some time pre- 

 vious to the commencement of the observation (from 2 P.M. on 

 previous day) and during it, no food was taken. In some of 

 the observations a day of complete muscular rest, in others a 

 day of considerable muscular exercise (a long bicycle ride), pre- 

 ceded the actual observation day. 



It was found that the urine collected during the work hour 

 already showed a small but yet distinct increase in the purin 

 bases, the amount of uric acid being, however, as yet not in- 

 creased. During the hour following the work hour, this increase 

 in the basic purins had very greatly increased, and the uric acid 

 had also begun to show some increase. During the second hour 

 following the work, the basic purin excretion had begun to de- 

 crease, but that of the uric acid had now become markedly raised. 

 After this time both the basic and acid purin excretions became 

 less, until, in about four hours after the work, the normal had 

 been reached, beyond which the excretion was subnormal for 

 some time, lasting even till the next day. On account of this 

 ultimate diminution in the excretion, it was found that the early 

 morning purin excretion was always less when muscular work 

 had been practised on the day previous to the observation than 

 when there had been muscular rest. It is no doubt on account 

 of this diminished excretion following the increase that very 

 little change has been found by other workers to occur in the 

 daily purin excretion when muscular work was practised : the 

 increased excretion due to work being followed by a subsequent 

 diminution, the total effect on the daily excretion would be 

 masked. 



In the second type of experiment, Burian perfused the muscles 

 of the hind limbs of a dog through the abdominal aorta (von 

 Frey's method) with defibrinated dog's blood diluted several 



