38 



Scientific Proceedings (109). 



amount of sodium hydroxide, the incubation temperature being 

 37° C. 



Results: (1) Bile from carrier rabbits of B. typhosus shows a 

 lower hydrogen ion concentration than that from normal animals. 

 In the first the general mean was 8.33 while the latter gave 7.41. 



(2) B. typhosus is viable in vivo in rabbit bile even when the 

 hydrogen ion concentration is depressed to P H 9.4. 



24 (1606) 



The conditions under which the ratio between the urea content 

 of the urine and of the blood remain constant. 



By T. Addis and D. R. Drury. 



[From the Laboratory of the Medical Division of Stanford Uni- 

 versity Medical School, San Francisco.] 



Simultaneous measurements of the hourly rate of urea excre- 

 tion and of the blood urea concentration have been made under 

 various conditions in man in order to determine whether the ratio 

 between the urine and blood urea ever becomes approximately con- 

 stant. After the administration of urea and large amounts of 

 water the ratio shows at first a considerable variability, but after 

 the maximum urea concentration in the blood has been attained 

 and the concentration is slowly falling the ratio becomes constant 

 for each individual within fairly narrow limits. Food, excitement, 

 and the various other factors produce marked variations even 

 under these conditions. We have not been able to confirm the 

 conclusion of Austin, Stillman and Van Slyke, that the ratio of 

 urea excretion varies with the square root of the volume of urine 

 when the blood urea concentration is constant. 



Under the special conditions outlined above, the rate varies 

 directly with changes in the blood urea concentration from 118 to 

 20 mgs. per 100 cc. 



