1906.] 



The Viscosity of the Blood. 



337 



species may differ among themselves, evidently if one desire to obtain strictly 

 comparable results under varying conditions, say of the effect of corpuscles 

 present, or of the effect of adding different quantities of the same or different 

 salts, and to draw trustworthy deductions from the results of such experi- 

 ments, it is absolutely essential that these experiments should, as far as 

 possible, be carried out with blood obtained from the same animal or human 

 specimen at one and the same time, and from the same part of the body, 

 whilst the experimental conditions should be such as to allow the greatest 

 amount of control of the particular influence it is desired to investigate. 

 Clearly a vein or artery, probably in an unsymmetrical position with variable 

 walls and connected directly to a complicated circulatory system with possible 

 fluctuations of pressure, is not the ideal place to study in the first instance, 

 say the effect of varying the number of corpuscles or that of different 

 quantities of any particular salt. 



The method we habitually adopted, after drawing up our scheme of experi- 

 ments, was to place into a number of wide-mouthed stoppered jars just so 

 much solution of a calculated strength of the anticoagulator chosen that, in 

 general, when the stoppered jar was brought under the open vein of the 

 animal and allowed to fill up to a definite mark, we knew that for every 

 95 c.c. of blood we had 5 c.c. of water and a known amount of the anti- 

 coagulator — or 5 c.c. of the anticoagulator when the same was not a water 

 solution, e.g., oil. (In the case of additions of MgS0 4 , more water was 

 present.) The jars thus filled were allowed to stand for two or three hours to 

 settle. A large quantity of the supernatant plasma was then drawn off and 

 centrifuged for two minutes. 



To successive portions of this clear centrifuged plasma systematic additions 

 of red cells were made, and a careful blood count taken from a well-shaken 

 portion of this artificial blood by means of a Thoma-Zeiss hsemocy tome ter, just 

 before the required amount was placed in the viscosimeters. 



Of the fairly representative group of anticoagulators we tried — viz., 

 potassium oxalate, sodium citrate, magnesium sulphate, peptone, leech 

 extract, and olive oil — the two first proved to be the most satisfactory for our 

 work. In Tables I and II will be found three series of observations made 

 with different concentrations of each of these two anticoagulators at different 

 temperatures and with varying numbers of red corpuscles suspended in similar 

 plasma. 



Under rj in each sub-section are tabulated in absolute units the values 

 found for the viscosity coefficient at the temperatures recorded in the first 

 column on the left, with a blood containing the number of corpuscles per 

 cubic millimetre stated at the head of the column. Under E is given the ratio 



