346 Dr. A. du Pre Denning and Mr. J. H. Watson. [May 7, 



find out which chemical bodies most strongly affect the viscosity of the blood 

 under certain conditions, since this is clearly of importance in considering 

 changes in the circulatory system. Mention may be made of the recent 

 researches of G-. Stodel on the biological importance of small quantities of 

 colloidal bodies in the treatment of certain infective diseases, etc. An 

 investigation of the effects of these bodies on the viscosity of the blood may 

 conceivably prove most profitable. 



A subsequent series of determinations some six days later gave practically 

 the same results. 



The Viscosity Coefficients for Various Plasmata and Sera obtained from the 

 blood of the same animal are placed together in Table IV, with the anti- 

 coagulator into which the blood was received at the head of each column. 



Table IV. — Showing Values of the Viscosity Coefficients found for 

 various Plasmata and Sera. 





Salted plasmata. 



Sera. 



Anticoagulator. 



"3 per cent, 

 potassium 

 oxalate. 



12 - 5 per cent. 

 MgS0 4 . 



Peptone. 



Leech 

 extract. 



Olive oil. 



C. 

 31 -8 

 35 -0 

 40-0 

 44 -5 



-0139 

 -0131 

 '0122 



-oiio 



-0141 

 -0134 

 -0124 

 -0115 



-0136 

 -0128 

 -0116 

 -0105 



-0126 

 -0119 

 -0104 

 -0098 



-0125 

 -0119 

 -0105 

 -0099 



With horses' blood, as is well known, there follows a rapid subsidence of 

 the corpuscles : consequently it was easy to siphon off small quantities of the 

 supernatant liquid from each specimen. In the case of the first two speci- 

 mens (namely, with potassium oxalate and MgS0 4 ) observations were taken 

 before coagulation had occurred, i.e., we were dealing with plasma ; whilst in 

 the case of the last three clotting had occurred before estimations were 

 attempted. Having found such small variations in the viscosity values for the 

 plasma and serum with the conditions under which these experiments were 

 made, we did not pursue this question further, inasmuch as our chief object 

 was to investigate those factors which play a predominant part in determining 

 the viscosity of the blood. 



The Effect of Varying the Capillary Bore. — When it is remembered that- 

 blood is really a very complex colloidal suspension or emulsion, containing 

 numerous particles, corpuscles, and other cellular elements, in a feebly viscous 

 matrix, we may well imagine that the rate of increase of the viscosity 

 coefficient with each fresh addition of corpuscles, etc., will depend largely on 



