ABSORPTION OF ISO TONIC FI UIDS. 305 
passage of lymph upwards and through the chest. We must therefore 
look to other methods fco decide this question. 
2. There is a whole scries of experiments made by other observers 
which I think prove conclusively the power of the blood vessels to take 
up fluid from the tissue spaces. If an animal he bled several times, it 
will be found that the blood obtained in the later bleedings is more 
watery than that obtained at the beginning of the experiment. Now 
this diminution of total solids in the blood seems to be due chiefly to a 
dilution of the serum ; the serum contains less solids than before, and is 
increased in volume relatively to the blood corpuscles. I may here 
quote some observations which show this point. 1 
Dog 11 "4 kilos. — Solids of serum = 7"72 per cent. Dog then bled to 
220 c.c. Thirty minutes later, solids of serum = 7T4 per cent. 
In another experiment the solids of the serum were at first 6 "98 per cent. ; 
after bleeding to 200 c.c. = 6*57 per cent.; after further bleeding to 100 c.c. 
= 6 '3 7 per cent. 
In a smaller dog (6*5 kilos.), withdrawal of 150 c.c. blood reduced the 
solids of the serum from 7 "7 7 per cent, to 6 "47 per cent. 
It must be noticed that this attempt to regulate the amount of the 
circulating blood by bringing it up to its normal volume is carried out 
with great rapidity, so that it is, even while an animal is being bled, 
found that the later portions of blood are more dilute than the earlier 
portions. That the fluid which is added to the blood in these cases is 
derived from the tissues or tissue spaces, is shown by Lazarus-Barlow's 2 
experiments. This dilution of the blood takes place even when the 
thoracic duct is tied or when the lymph is conducted away by placing a 
cannula in the duct, so that it cannot be due, as was formerly thought, 
to an increased lymph flow into the blood. 
3. In order to be absolutely certain of the power of the blood 
vessels to take up isotonic solutions and dropsical fluids from the 
tissue spaces, I carried out a series of experiments, 3 in which I led 
defibrinated blood through the blood vessels of amputated limbs. In 
each case I had a double set of transfusion apparatus, and sent one-half 
of the blood many times through a limb which had been rendered 
dropsical by the injection of isotonic salt solution, while simultaneously 
fluid was flowing at the same pressure through the other limb, which was 
not dropsical, and thus served as a control. In each case the blood was 
analysed and its haemoglobin estimated before the experiment, and from 
both limbs after the experiment. It was invariably found that, whereas 
the blood which had passed from twelve to twenty-five times through 
the sound limb had become rather more concentrated, the blood which 
had passed through the cedematous limb had taken up fluid from this 
limb. I may here quote one of these experiments as an example : — 
Total Percentage 
Solids. of Oxyhemoglobin. 
1. Blood before experiment . . 21 -2 per cent. 100 
2. After twenty passages through 
normal leg . . . . 21 - 4 „ „ 103 
3. After twenty passages through 
oedematous leg . . . . 20"5 ,, „ 95 -5 
1 Tscherewkow, Arch. f. d. ges. Physiol., Bonn, 1895, Bd. lxii. S. 304. 
- Journ. Physiol., Cambridge and London, vol. xvi. p. 13. 
3 Ibid., 1895, vol. xix. p. 312. 
VOL. I. — 20 
