107 



ANNOTATION 



Ohs. 78. Repeats the observations by 

 which Claude Bernard, Brown Sequard, 

 and the elder Waller discovered the exist- 

 ence of vasoconstructor nerves. Bernard 

 {Comptes rendus de la Soc. de Biologie, p. 163 ; 

 Paris, 1851) observed that section of the 

 cervical sympathetic was followed by vascular 

 dilatation and rise of temperature in the 

 corresponding- ear (rabbit), and {Comptes 

 rendus de la Soc. de Biologie ; Paris, 

 Oct. -Nov. 1852) that galvanization of the 

 upper stump of the cut nerve caused vaso- 

 constriction and fall in temperature of the 

 ear. In August 1852 this latter fact had 

 been announced by Brown Sequard from in- 

 dependent observations [Philadelphia Medi- 

 cal Examiner). A. Waller, almost at the 

 same time and independently, observed it and 

 communicated it to the Acad, des Sciences, 

 Paris [Comptes rendus, Feb. 28, 1853). 

 Bernard regarded the change in temperature 

 as more or less independent of the vascular 

 change ; Waller considered the change in 

 temperature secondary and consequential 

 to the vascular change ; subsequent know- 

 ledge has confirmed the latter view. 



Ohs. 79. Withdrawal of blood from the 

 circulation even rapidly, as by arterial 

 haemorrhage, up to 25 per cent, of the total 

 blood does not produce much fall in the 

 A. P. The pressure is maintained by vaso- 

 motor adjustment of the vascular tone and 

 more gradually by the circulating blood 

 absorbing fluid from the tissues. Loss of 

 more than 35 per cent, of the total blood 

 does, however, seriously lower the A. P. It 

 may be assumed that an adult cat in good 

 nutrition has 50 c.c. blood per kilo of its 

 weight. This is a higher percentage than 

 was arrived at in man by Haldane and 

 Lorrain Smith [Jnl. of Physiol, vol. xxv, 

 p. 331, 1899). It has been shown, however, 

 by G. I. Dreyer and W. Ray [Phil. Trans. 



B. vol. cci, p. 133, 1910 ; vol. ccii, p. 191, 

 1911) that the blood-volume of warm-blooded 

 animals is a function of the body-surface. 

 Smaller animals having a relatively greater 

 body-surface than larger, have also a relatively 

 greater blood-volume. The formula arrived 

 at by G. Dreyer and E. W. Ainley Walker 

 [Skand. Arch. f. Physiol, vol. xxviii, p. 299, 

 1913, and Proc. Boy. Soc. B. vol. xxxvii, 

 p. 319, 1914) is B = W %, where B is the 

 blood-volume in grm., W the animal's weight 

 in grm., n is approximately -72, and h a 

 constant for each species, and not yet deter- 

 mined for the cat. 



Ohs. 80. To counteract the effects of 

 severe haemorrhage, Richard Lower, applying 

 Harvey's discovery of the blood-circulation, 

 devised the operation of transfusion. He 

 carried out the experiment first in 1665, at 

 Oxford. He transfused blood directly from 

 the carotid of one dog into the jugular vein 

 of another. He used two short silver tubes 

 tied into the above vessels and connected 

 them by a piece of freshly-excised artery 

 [Phil. Trans. Boy. Soc. vol. i, p. 353 ; London, 

 1666. Tractatus de Corde, cap. iv, p. 174 ; 

 London, 1669). Lower's method proved 

 efficacious, and Denis of Paris employed it 

 successfully in the following year, transfusing 

 from a lamb into a man. The method has, 

 however, dangers, e.g. in travascular clotting, 

 haemolysis, &c., to which the chemical 

 knowledge of the time was not adequate. 

 Recourse was subsequently taken to intra- 

 venous injection of 'normal' saline solutions. 

 A previous exercise (exerc. X) showed that 

 'normal' saline injected per venam is not 

 retained in circulation, but transudes through 

 the capillary walls almost as rapidly as it is 

 introduced. Nor does it restore that part 

 of the blood's osmotic tension due to the 

 protein colloids (Starling, 1896, Jnl. of 

 Physiol, vol. xix, p. 312 ; Scott, 1916, ibid. 



P 2 



