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



In 1894, Graham Brown, writing in the Edinburgh Hospital Reports " On 

 the Changes in the Circulation produced by a Eise in Temperature," pointed 

 out the great diminution in the viscous resistance that occurs when 

 defibrinated blood is made to pass through tubes heated to fever temperature, 

 and applied his results to the explanation of certain phenomena of fever. 



Brown also found that if defibrinated blood be rendered lake-coloured by 

 alternately freezing and thawing, the rate of flow was increased, and that at 

 varying temperatures the behaviour of the blood then approached tolerably 

 close to that calculated by the Eoiseuille formula.* 



Hiirthle, alone in 1896, and later with Eussell Burton-Opitz, determined 

 the values of the viscosity coefficient of the blood of different living animals 

 by allowing it to flow directly from the carotid through a calibrated tube — 

 simultaneous measurements of the outflow time and of the blood pressure 

 being made. As a result of these experiments Hiirthle states that (1) the 

 coefficient of viscosity in any one species of animal is practically constant : 

 that of a dog = 4*5 the value for water at 37° C. ; that of a cat = 4*1, and 

 of a rabbit = 3"2 ; and that (2) almost identically the same values were found 

 for the viscosity of the blood of one and the same individual animal when 

 tubes of various sizes and varying arterial pressures were employed — " from 

 which we are to conclude that the suspension of the corpuscles in the blood 

 does not seriously affect the application of Eoiseuille's law to it as a fluid, "-f- 



E. Burton-Opitz, using Hiirthle's instrument, found that intravenous 

 injections of 0*7 per cent, saline caused an immediate and very distinct 

 decrease in the viscosity, whereas equal amounts of distilled water apparently 

 rendered the blood slightly more viscous. Further, the introduction of 

 alcohol, either directly into the circulation or into the digestive tract, always 

 rendered the blood more viscous : a much greater and more lasting increase 

 appeared when the alcohol was injected into the stomach or duodenum.^ 



Hirsch and Beck, employing a modified form of an Ostwald's viscosimeter 

 connected to a constant-pressure apparatus, examined directly the blood of 

 a number of persons : as a mean of their results, they suppose the normal 

 value for the viscosity of human blood to be about five times that of water 

 at 38° O, the lowest value they give being twice, and the highest nine 

 times that of water. By means of this same instrument they examined the 

 blood of 24 patients suffering from nephritis, but were unable to draw any 

 definite conclusions.! 



* Graham Brown, 'Royal Infirmary Reports,' Edin., 1894. 



t Professor C. S. Sherrington, on Cardiac Physics, ' Allbutt's Medicine,' vol. 5, p. 476 ; 

 Hiirthle, ' Deutsch. Med. Wochenschr.,' August, 1897. 

 I Burton-Opitz, ' Pfliiger's Archiv,' vol. 87, 1900. 



§ Hirsch and Beck, ' Deutsch. Arch, fur Klin. Med.,' vol. 69, p. 503, 1901, etc. 



