84 



THE CAPILLARY TISSUE. 



tral organ for propelling the blood, the second conveying 

 it to every part of the system, while the third returns it 

 back again to the heart. 



Besides this general circulation, there is also distin- 

 guished the pulmonary, the portal, the capillary and the 

 lymphatic circulations. 



The vascular tissue belonging to each of these circula- 

 tions will be examined in the order of their development, 

 which physiology shows to be 



1. The Capillary. 



2. The Portal. 



3. The General. 



4. The Pulmonary. 



5. The Lymphatic, an appendage to the blood circulation. 



THE CAPILLARY TISSUE. 

 FIG. 5. 



The capillary tissue (from capillus, a hair,) is situated 

 between the arteries and the veins, at the termination of 

 the one and the commencement of the other. 



FIG. 5 shows the capillaries between the termination of the arteries and the 

 commencement of the veins in a frog's foot. Magnified three diameters, aa 

 the veins ; 66 the arteries. 



