336 



PHYSIOLOGICAL REGULATIONS 



ties as to whether all the oxygen apportioned to carbohydrate 

 represents glucose burned. In addition, whatever the portion of 

 glucose that passes to carbon dioxide, much more glucose may be 

 continuously formed and transformed in many processes of inter- 

 mediary metabolism, and the turnover of glucose recognized for the 

 whole body may be but a small part of the sums of all the local for- 

 mations and transformations of this chemical compound. The 

 dog's turnover has been estimated at 0.25 gm./kg. hr. (Reid, '36), 

 and is the same in depancreatized individuals. 



Glucose content, at least of the blood, is less variable than con- 

 tents of many other components (table 38). According to data of 



TABLE 38 



Sugar concentrations in Hood under standard conditions, 

 made on a separate day 



Each observation was 



Species 



Dog 

 Man 



Rabbit 



Number of 

 individuals 



1 



23 



23 



141 



100 

 27 



Source of data 



Wierzuchowski ('37b) 

 Okey andRobb ('25) 



i c 



Pierce and Scott ( '28) 



Eadie ('23) 

 Clough et al. ('23) 

 Scott and Ford ('23) 

 Scott ('27) 



Wierzuchowski ( '37b) almost no variations are detectable in a dog 

 at hourly intervals, nor even at the close of a day of loading and 

 unloading of glucose. Adrenalectomy does not increase the vari- 

 ation of blood sugar concentration from day to day (data of Zucker 

 and Berg, '37). Among species, the rabbit (table 38) in contrast 

 to dog and man, shows higher content and greater variability. 

 That contrast represents a difference in maintenance ; yet hereto- 

 fore rabbit and dog have been studied indiscriminately. 



The data yield a glucose-time system of four variables (AC, 

 SC/At, t, 1/At). At diverse loads and rates of loading, character- 

 istic latent periods, times to maximal rates, and initial rates of 

 disappearance are found (figs. 163 and 164), all of which are com- 

 parable to the temporal characteristics of the dog's water-time sys- 

 tem with continued administrations (§12). The velocity quotients 

 (1/At) for the total glucose exchange (fig. 167), are more constant 

 with time in slow infusions than in rapid. Evidently after the first 



