174 THE FLUIDS. 



in hsematine. The fibrine coagulates more slowly, and is richer in 

 fat; the serum is denser,^ sometimes even exhibiting a milky tur- 

 bidity from an abundance of fat-globules (Fig. 

 Fig. 103. 103) and cytoid corpuscles. The fat, albumen, 



extractive matters, and the salts of the serum 

 are also pretty uniformly augmented. 



5. Among the lower animals, the blood of 

 the omnivora (hog, &c.) is the most abundant 

 in corpuscles (and therefore in soluble phos- 

 phates of iron) ; birds are next in order ; then 

 the carnivora and the herbivora. Of fibrine, 

 the blood of birds contains the most ; then 

 that of the omnivora, herbivora, and the carnivora. Of fat, the blood 

 of birds also contains most ; then the carnivora and the herbivora. 

 The blood of the mammalia contains more albumen than that of 

 birds. The solid constituents of the serum also preponderate in the 

 omnivora. In the cold-blooded vertebrata (fishes and amphibia), the 

 blood is poorer in corpuscles and richer in water than in the warm- 

 blooded. 



Normal Differences in Composition of the Blood in different Vessels. 



A. In arterial blood the red corpuscles are less numerous than in 

 venous blood (Kolliker), and contain more water and less solid con- 

 stituents; though they have relatively more hasmatine and salts, 

 but far less fat. The white corpuscles are also less numerous. (Kol- 

 tiker.) The intercellular fluid of the arteries is richer in fibrine 

 than that of venous blood, and its serum contains somewhat more 

 water and less albumen 1 and fats; while their extractive matters are 

 slightly increased, and the salts still more so. Arterial blood also 

 contains more oxygen, but only relatively to its carbonic acid gas 

 (p. 164). It absolutely contains more of both these gases than 

 venous blood, and about the same amount of nitrogen (pp.44, 164). 



B. The blood of certain veins is peculiar. 



1. The portal vein. During digestion, if sufficient drink has been 

 taken with the food, the portal blood is rich in intercellular fluid 

 and in water, and the number of blood-cells is therefore small. The 

 fibrine is slightly, and the fat considerably, increased; while the 

 albumen, extractive matters, and salts are moderately so. Compared 

 with the blood of the jugular vein, the portal blood is poor in cells 



1 In the solid constituents alone of the serum, an equal quantity of albumen is 

 found in arterial and venous blood. (Lehmann.) 



