URETER PRESSURE. 181 



10. In no case was secretion in any quantity observed with a lower 

 blood-pressure, as asphyxia owing to the blood-dilution intervened. I do 

 not doubt however that it might occur under more fortunate conditions. 

 Indeed Gottlieb and Magnus report a case in which in a rabbit under 

 continuous intravenous injection of saline, and a fall of blood-pressure 

 due to chloral, 0'3 c.c. of urine was secreted in 5 min. with a blood-pressure 

 of less than 30 mm. Hg. As the plasma must have been greatly diluted 

 this exceedingly small secretion does not appear impossible though 

 very exceptional. As pointed out above, the measured urinary pressure 

 (the minimum difference was but 6 mm.) was probably far too high. 

 The further secretion of one drop of urine with a blood-pressure 

 16 13 mm. Hg, difference of 3 mm., has of course little significance, as 

 such at times appears before death under such conditions and probably 

 is due to an emptying of kidney pelvis and ureters. 



This experiment, with the other examples given in brief in the 

 addenda, points clearly it seems to the constitution of the plasma and 

 especially of its proteid constituent having a marked influence on the 

 relation which subsists between ureter-pressure and blood-pressure, and 

 goes to justify the explanation given by Starling of the lack of secretion 

 with low blood-pressure, i.e. less than 30 mm., and of the occurrence of a 

 minimum difference of about the same amount between blood and ureter- 

 pressure when the plasma is normal in its proteid content. 



A third factor which definitely affects the ureter-pressure, and that 

 in two distinct ways, is the rate of production of urine. The first effect 

 of a more rapid production of urine is a more rapid rise of the ureter- 

 pressure. This may be distinctly seen in Fig. 6 A and B. This is of 

 course principally due to the fluid necessary to cause the rise being 

 more rapidly supplied and to a less extent to the fact that dilated kidney 

 vessels will occupy more of the space within the capsule and allow but 

 a small dilation of the tubules. In exp. XVI., Fig. 6, Rabbit 2'6 kg., 

 the more rapid flow of urine was produced by an injection of 2 c.c. 

 of 10/ solution of caffeine sodium salicylate. A mercury-valve con- 

 nected with one carotid prevented the blood-pressure rising above its 

 previous maximum. The ureter manometer connections were not closed 

 until the blood-pressure and urinary flow had become constant. Curve B 

 in exp. IX., Fig. 5, was obtained soon after an injection of normal saline. 

 The ureter manometer connections were then broken, the animal bled 

 125 c.c., the connections again closed and curve C obtained. It is to be 

 noted that the blood-pressure is approximately the same, and the con- 

 stitution of the plasma has altered but little, haemoglobin indices 47 / 



