BLOOD IN DIFFERENT VASCULAR REGIONS. 335 



perhaps only in the serum. The small traces of bile acids occurring in 

 normal blood, according to CROFTAN, 1 are contained in the leucocytes. 



The calcium occurs, with the exception perhaps of the blood cor- 

 puscles of the ox, only in the plasma and the same applies at least for 

 the principal part of the magnesium. The division of the alkali between 

 the blood-corpuscles and the plasma is very different, namely, the blood- 

 corpuscles of the pig, horse and rabbit contain no sodium, the human 

 corpuscles are richer in potassium and those of the ox, sheep, goat, dog 

 and cat are much richer in sodium than potassium. Chlorine occurs in 

 greater abundance in the serum of all animals than in the blood-corpuscles. 

 The iodine only occurs in serum, while iron regularly, almost without ex- 

 ception occurs in the form-elements, especially in the erythrocytes. As the 

 nucleoproteins contain iron, some iron occurs in the leucocytes and traces 

 of iron also occur in the serum. This quantity is very small under normal 

 conditions while in disease the relationship between the haemoglobin- 

 iron and the other blood-iron may, it seems, changes very distinctly. 

 Manganese has also been found in the blood, as well as traces of lithium 

 copper, lead, silver, and also arsenic in menstrual blood. The entire 

 blood contains in ordinary cases 770-820 p. m. water with 180-230 

 p. m. solids, among these 173-220 p. m. are organic and 6-10 p. m., 

 inorganic. The organic consist, after substracting 6-12 p. m. extractives, 

 of protein and haemoglobin. The quantity of the latter in man is 130- 

 150 p. m. In the dog, cat, pig and horse the hemoglobin content is 

 about the same; in ox, bull, sheep, goat and rabbit blood it is lower 

 (ABDERHALDEN). 



The Composition of the Blood in Different Vascular Regions and under 



Different Conditions. 



Arterial and Venous Blood. The most striking difference between 

 these two kinds of blood is the variation in color caused by their con- 

 taining different amounts of gas and different amounts of oxy haemoglobin 

 and haemoglobin. The arterial blood is light red; the venous blood is 

 dark red, dichroic, greenish by transmitted light through thin layers. 

 The arterial coagulates more quickly than the venous blood. The latter, 

 on account of the transudation which takes place in the capillaries, was 

 formerly said to be somewhat poorer in water but richer in blood-cor- 

 puscles and haemoglobin than the arterial blood; but this is denied by 

 modern investigators. According to KRVGER 2 and his pupils the quan- 



1 Pfliiger's Arch., 90. 



2 Zeitschr. f . Biologie, 26. This also gives the literature on the composition of 

 the blood in different vascular regions. 



