40 A Manual of Veterinary Physiology. 



blood is contained has an effect on the rapidity of the 

 process ; a deep vessel retards coagulation, whilst a rough 

 and shallow one promotes it. 



The Extractives of the Blood are fats, cholesterin, lecithin, 

 creatin, urea, hippuric and uric acids, grape sugar in small 

 and varying quantities. Fats occur as neutral fats, olein, 

 stearin, and palmatin. The amount of fat in the blood 

 during digestion is '4 to -6 per cent. ; in fasting animals, 2 

 per cent. ; in dogs fed on a fatty diet it may reach 1'25 per 

 cent. (Landois and Stirling). Schmidt states that there is 

 twice as much fat in the serum of recently fed horses as 

 in the serum of those kept starving. Soaps to the extent 

 of -05 per cent, to *1 per cent, are found; urea, -02 to -04 

 per cent.; sugar, -1 to -15 per cent. Bilirubin has been 

 found in the serum of the blood of calves (M'Kendrick). 



The Difference between Arterial and Venous Blood is that 

 the former contains more oxygen and less CO., ; arterial 

 blood also contains more water, fibrin, extractives, salts, and 

 sugar, fewer blood corpuscles, and less urea; its tempera- 

 ture is, on an average, 1° C. lower (Hermann). 



The dark colour of venous blood is not due to the greater 

 amount of C0 2 it contains, but to the diminution of oxygen 

 in the red blood-cells. The alteration in colour effected by 

 the addition of reagents and gases to blood, is probably due 

 partly to alterations in the shape of the corpuscles them- 

 selves, which become more concave on the addition of 

 oxygen and less concave on its removal: and to the fact 

 that oxy-lneinoglobin is brighter than reduced. 



The Salts of the blood are divided between the plasma 

 and the corpuscles; the distribution of the salts in these 

 is not the same in all animals; in the horse and pig, for 

 example, sodium only exists in the plasma and none in the 

 Corpuscles, whereas in the ox and dog belli corpuscles and 

 plasma contain sodium; the salts of the red cells in man 

 and the pig consist, principally of potash, chlorides, and 

 phosphates; in the ox potash and phosphates are small, 

 lime is absent, whilst, soda is huge. In this connection the 

 following table from Gamgee is interesting : 



