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EXPERIMENTAL PHYSIOLOGY 



almost single file. Do these show pulsations? Trace the flow 

 from these into larger vessels where no pulsation is evident. 



2t 



Fig. 33. — Capillary Circulation in the Web of a Frog's Foot, X 100: a, 6, small veins, 

 d, capillaries in which the corpuscles are seen to follow one another in single series; 

 c, pigment cells in the skin. 



Note the direction of flow in these tubes. What is the name 

 of these tubes? Define artery, vein, and capillary in terms 

 of the direction of blood flow. 



XL VI. — Minute Structure of Arteries and Veins 



(Optional). 



Apparatus. — Prepared slides of cross sections of arteries and 

 veins, compound microscope. 



Directions. Note that both artery and vein have three 

 coats: a fining of epithelial ceUs called here endothelium , a 



