26 COMPOSITION OF THE RED CORPUSCLES. [BOOK i. 



The fats, which are scanty, except after a meal or in certain 

 pathological conditions, consist of the neutral fats, stearin, pal- 

 mitin, and olein, with a certain quantity of their respective alkaline 

 soaps. Lecithin 1 and cholesterin occur in very small quantities only. 

 Among the extractives present in serum may be put down all the 

 nitrogenous and other substances which form the extractives of the 

 body and of food, such as urea, kreatin, sugar, lactic acid, &c. A 

 very large number of these have been discovered in the blood 

 under various circumstances, the consideration of which must be 

 left for the present. The peculiar odour of blood-serum is pro- 

 bably due to the presence of volatile bodies of the fatty acid series. 

 The faint yellow colour of serum is due to a special yellow pigment. 



e most characteristic and important chemical feature of the 



ine constitution of the serum is the preponderance of sodium 



In this respect the serum offers a 

 Less marked, but 



salts over those or potassium. 



marked contrast to the corpuscles (see below). 



still striking, is the abundance of chlorides and the poverty of 

 phosphates in the serum as compared with the corpuscles. The 

 salts may ia fact briefly be described as consisting chiefly of 

 sodium chloride, with some amount of sodium carbonate, or more 

 correctly sodium bicarbonate, and potassium chloride, with small 

 quantities of sodium sulphate, sodium phosphate, calcium phos- 

 phate, and magnesium phosphate. And of even the small quantity 

 of phosphates found in the ash, part of the phosphorus exists in 

 the serum itself not as a phosphate but as phosphorus in some 

 organic body. 



Composition of the red corpuscles. The corpuscles contain less 

 water than the serum, the amount of solid matter being variously 

 estimated at from 30 to 40 or more p. c. The solids are almost 

 entirely organic matter, the inorganic salts in the corpuscles 

 amounting to less than 1 p. c. Of the organic matter again by far 

 the larger part consists of haemoglobin. In 100 parts of the dried 

 organic matter of the corpuscles of human blood, Hoppe-Seyler 

 and Jiidell found, as the mean of two observations, 



Haemoglobin 90*54 Lecithin '54 



Proteid Substances 8'67 Cholesterin '25 



There are reasons for believing that not only may the number 



of red corpuscles vary, but also the quantity of haemoglobin present 



in the corpuscles differ under different circumstances. Malassez, 



by comparing the tint of a quantity of blood the numbers of whose 



corpuscles had been estimated, with that of a graduated solution 



of picrocarminate of ammonia, has been able to estimate the 



amount of haemoglobin present in the corpuscles under different 



circumstances. He finds that in anaemia the poverty of the 



1 For detailed accounts of the characters of the several chemical substances 

 mentioned in this and succeeding chapters consult the Appendix under the appro- 

 priate headings. 



