60 PHYSICAL CHARACTERS OF SERUM. SERUM-GLOBULFN. [BOOK I. 



fifteen minutes after the meal, was turbid; the serum from the third 

 bleeding, eight hours and fifteen minutes after the meal, was still thicker ; 

 while that from the last bleeding eighteen hours after the meal,, was again 

 limpid, although some supper had been eaten in the interval. 



" The young man first mentioned, after fasting eighteen hours,, dined 

 upon sixteen ounces of brown soup, four ounces of bread, eight ounces 

 of potatoes, twenty ounces of beef-steak, and sixteen ounces of London 

 porter, and fasted eighteen hours after the meal. He had blood taken 

 from his arm four times to the extent of two ounces each time. The 

 serum of the blood first taken, immediately before the meal, was of an 

 amber yellow and quite transparent ; the serum from the second bleeding, 

 two hours and ten minutes after the meal, was turbid ; the serum from 

 the third bleeding, eight hours after the meal, was exactly of the colour 

 of water gruel and quite opaque ; the serum of the blood last taken, 

 eighteen hours after the meal, was still turbid, its limpidity not having 

 been, as after his usual fare, restored by an eighteen hours fast." 



The milkiness of such blood is due to finely divided fat which often 

 may be observed to float to the surface and presents the appearance 

 of oil globules or drops. 



The specific gravity of the serum obtained from human blood 

 varies between 1027 and 1032, but is on an average 1028. Its re- 

 action is alkaline, and its alkalinity is greater than that of the plasma. 



1000 grammes of blood yield between 440 and 525 grammes of 

 serum (Gautier). 



Serum contains roughly about 10 per cent, of solid matters in 

 solution ; of these the most abundant are proteid in nature, the 

 chief being serum-albumin ; in addition to the proteids, the serum 

 holds in solution small quantities of nitrogenous matters soluble 

 in alcohol, which are technically grouped under the term extractives or 

 extractive matters, fats, sugar, inorganic salts and certain gases. These 

 various constituents will now be discussed in detail. 



TH-E PROTEIDS OF THE SERUM. 

 1. Serum-globulin or Paraglobulin. 



This constituent has been already discussed at considerable length 

 in relation to the subject of coagulation, and the reader is referred to 

 page 37 for the method of obtaining it from serum, as well as for 

 a discussion of the views which have been held as to its origin. 



It was formerly held that serum-globulin was present in much 

 smaller quantities in the serum than serum-albumin. According 

 to Hammarsten, however, the older methods employed in the 

 separation of this substance were insufficient. He has discovered 

 that magnesium sulphate effects the complete precipitation of serum- 

 globulin, and therefore admits of the accurate determination of 

 its amount. In the following table are shewn the results of analyses 



