ABSORPTION OF ISOTONIC FL UIDS. 305 



passage of lymph upwards and through the chest. We must therefore 

 look to other methods to decide this question. 



2. There is a whole series 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 be 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 = 7*14 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*37 per cent. 



In a smaller dog (6 '5 kilos.), withdrawal of 150 c.c. blood reduced the 

 solids of the serum from 7*77 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 oedematous limb had taken up fluid from this 

 limb. I may here quote one of these experiments as an example : 



Total Percentage 



Solids. of Oxy haemoglobin. 



1. Blood before experiment . . 2 1*2 per cent. 100 



2. After twenty passages through 



noimal 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. Ixii. S. 304. 



2 Journ. Physiol. , Cambridge and London, vol. xvi. p. 13. 



3 Ibid., 1895, vol. xix. p. 312. 

 VOL. I. 20 



