226 Dr. Buchanan on the White or Opaque Serum of the Blood. 



Table III. — Annual Premiums for Assurance of £100 on Select Lives, 

 Assuming Money to be improved at Four per cent, deduced from the 

 preceding Table. 



L. — On the White or Opaque Serum of the Blood. Bj Andrew 

 Buchanan, M. D., Professor of the Institutes of Medicine in the Uni- 

 versity of Glasgow. 



It is well known to all who have been in the habit of examin- 

 ing the characters of the blood, that the serum which separates from 

 it, instead of being transparent and of a yellow colour as we usu- 

 ally find it, is sometimes opaque and turbid, white as if milk had been 

 diffused through it, or otherwise discoloured. Such serum is usually 

 spoken of as white or milky serum. My present intention is to submit 

 to the Society a few observations as to the causes in which this re- 

 markable appearance of the serum of the blood originates. 



It has been affirmed, that the blood itself is sometimes of a milky 

 colour as it issues from the veins, or exhibits white streaks diffused 

 through its dark-red substance. That this latter appearance is some- 

 times observable within the blood-vessels of live animals, more espe- 

 cially in the vicinity of the heart, and that it is occasioned by the chyle 

 mingling but not yet incorporated with the blood, we have the testi- 

 mony of various physiologists, as of Pecquet, who by tracing the white 

 fluid to its origin, was led to the discovery of the two great trunks by 

 which the lymphatic vessels communicate with the blood-vessels. 

 In human blood flowing from the veins, I have never seen either 

 white streaks or diffuse whiteness. I have indeed heard of such 

 appearances being observed, but I am satisfied that they must be 

 of very rare occurrence from my having looked for them so often 

 in vain in the circumstances in which, as is shown below, they were 

 most likely to have presented themselves. It appears to me, there- 



