Dr. Buchanan on the White or Opaque Strum of the Blood. 227 



fore, probable, that the indefinite expressions *' white" or "milky 

 blood,*' employed by Haller, and by many other writers before and 

 since, must refer chiefly to the white state of the serum. This is 

 certainly the meaning of some of the authors quoted by Haller, as 

 of Tulpius, who conceived the white matter in the serum to be ab- 

 sorbed milk, and warns his patient against that beverage in time to 

 come. Haller himself, however, takes no notice of this colour of the 

 serum, and many of his expressions obviously imply a belief that the 

 whiteness was an attribute of the whole mass of blood.* The only 

 appearance, so far as I have ever seen, which could justify the appli- 

 cation of such epithets to the blood, is that observed in inflammatory 

 blood, which, when just about to coagulate, becomes whitish or bluish 

 upon the surface. But this affords no solution of the difficulty as 

 to the words of Haller, who expressly states that he omits all consi- 

 deration of such blood.t We are therefore unwillingly compelled 

 to recollect, that the same great physiologist, after a laborious exami- 

 nation of the arguments on both sides, declares that there is little or 

 no difference in appearance between arterial and venous blood ; and to 

 conclude that the observations then made as to the colour of the blood 

 were not worthy of implicit reliance. 



Hewson introduced a more accurate mode of speaking of these phe- 

 nomena, by referring the whiteness to the serum, and not to the 

 general mass of blood. Hewson, also, first minutely described this 

 condition of the serum, and analysed the circumstances on which it 

 appeared to him to depend. He rejects the opinion, which was preva- 

 lent previous to his time, that the white colour was owing to unassimi- 

 lated chyle circulating in the blood vessels. He ascribes it, on the 

 contrary, to fat absorbed from the adipose tissue, which he supposes to 

 be taken up more rapidly than the wants of the system require, and, 

 therefore, to accumulate in the blood vessels. He further regards the 

 phenomenon as generally connected with a state of disease ; as with 

 plethora, or a stoppage of natural evacuations. Such has been the 

 authority of the name of Hewson, that both these opinions have been 

 taught in the schools of physic ever since his time, and are generally 

 received by the most eminent physicians of the present day. John 

 Hunter stands almost alone in rejecting Hewson 's doctrine, that the 

 whiteness of the serum is owing to absorbed fat, " which," he says, "is 

 certainly not the case ; for it is not the same in all cases :" by which I 

 understand him to mean, that the characters of white serum are not 

 sufficiently uniform to warrant the supposition, that the colour is always 

 occasioned by the same substance. Hunter also rejects the opinion 

 that the white colour is due to unassimilated chyle ; " because, it does 



* Nempe in vivis animalibus, chylum albo suo colore conspicuum, ssepe per vasa san- 

 guinea oberrare, de vulnere fluere, ant in cor ipsum apertnm de auricula efiundi vidL Tom, 

 ii. p. 14, Element. Phys. 



t Id. ibid. 



