1922.) “ Renal Portal ’’ System. 109 
— time of the experiment 17:0 gms. and H 22°5 gms.) during 
x days was 0°01879 gm.,' while that of one pair of control 
ree (body- -weights at time of experiment = 17:0 gms. and 20-2 
gms.) during the same period was 0:°01100 gm., and that of 
another pair. of control toads OST: weights at time of experi- 
ment =17°2 gms. and lL ms.) during the same period was 
001822 gm. Thus, again, the ieee of the Toads G and H 
(deprived of a venous supply) each excreted as much nitrogen 
in a given time as each of the kidneys (retaining their venous 
supely): . four control toads. 
ing one month I estimated the nitrogen strengths of 
phe pais es of urine* (volume of an average sample =0°35 
.c ) obtained from the Toad G, which were 0:00046 gm. in 1 
c c., 0:00093, 000506 and 0-00220, the average nitrogen 
strength of which is 0:00216 gm. in 1 c¢.c. The corresponding 
nitrogen strengths of eight samples of urine (volume of an 
average sample = 0°55 c.c.) obtained during the same period 
from the Toad H were 0°00106 gm., 0:00180, 0:00100, 0°00276, 
0:00071 0:00114, 0°00256 and 000393. the average nitrogen 
strength of which is 0°00187 gm. inl c.c. And from the Toad J 
(about three weeks after the operation and therefore long before 
the two renal afferent veins could have been regenerated) the 
nitrogen strengths of ee samples of urine (volume of an 
average sample=0°68 c.c.) during the same period were 
0:00094, gm., 0°00075, “0-00128, 000053 pos 0°00106, the ~ 
average nitrogen strength of which is (-00091 gm. in | c.c. 
In one normal control toad the nitrogen strengths of five 
obtained during the same period were 0:00096 gm., 9°00156, 
000084, 0°00088 and 0-017, the average nitrogen strength 
of which is 000119 gm. in 1 c.c., and the nitrogen strengths of 
single samples of urine (average volume of which=0°47 c.c.) 
obtained from nine other control toads (kept under precisely 
the same conditions) were 0:00130 gm., 0:00120, 0:00072, 
0:00012, 0:00068. 000100, 00026, 0:00030 and 0°00080, the 
Toads G, H and J (with kidneys deprived of a venous supply) 
were neither less in volume nor deficient in nitrogen s —— 

lit will be noticed that this quantity is considerably less shan: poe 
quantity excreted by the asngie toad F in five days. The difference is due 
to the fact that the Toad F and its controls were fed on house-flies (a 
highly nitrogenous diet), while the Toads G and H and their controls 
mples of urine from toads and frogs can easily tained by 
iain a & nimal over a funnel and saleiag a the belly gets a dilute 
acid, when urine is almost immediately squirted, the bladder being it 
emptied. With ordinary toads and frogs : Sess one dilute sulphuric but 
this injures the skin in time: with experimental toads I use nos juice, 
which however is not quite so effective. 
