.76 ANTHROPOLOGY. 



munis; * and *, peronasus long us ; ^ and ', peronoeus brevis; ', extensor 

 communis brevis ; ^' and \ peronceus tertius ; ", annular ligament on the 

 back of the foot. Fig. 17 ', flexor digitorum brevis ; ^ abductor pollicis ; 

 ', flexor pollicis brevis ; ', abductor digiti minimi ; ^, flexor brevis digiti 

 minimi. Fig. 18 \ flexor pollicis brevis ; '•', adductor pollicis ; ', transver- 

 salis plantaris; \ tendon of the peronseus longus. Fig. 19 interosseous 

 muscles of the back of the foot. 



ni. THE VASCULAR SYSTEM. 



(ANGEIOLOGY.) 



The Vascular System consists of membranous ramifying tubes, which 

 conduct either blood or fluids to be added to the blood for the sake of 

 restoring to it the materials necessary for its normal functions. The blood, 

 from which is derived the material of life and growth, is furnished by the 

 food taken into the stomach, which after undergoing certain operations, 

 subsequently to be explained, and after being strained through exceedingly 

 fine tubes called lacteals, is introduced into the general circulation by the 

 thoracic duct. The blood circulates through all parts of the body mainly 

 by the impulsion of a central engine, the heart, which continues pulsating 

 at regular intervals during the entire life of the animal. Vessels which 

 conduct blood from the heart are known as arteries, while those which 

 bring it back again are veins. The former are distinguishable from the 

 latter by their exhibiting the phenomena of pulse. The arteries pass to all 

 parts of the body, dividing and subdividing continually as they recede from 

 the heart, until liually they end in ramifications so fine as only to be appre- 

 ciable by the microscope. These terminal branches are called capiUaries. 

 The capillaries are continued into the veins, which present an appearance 

 much like that of the arteries, viz. a tree excessively ramifying, with the 

 trunk resting on the heart, and the branches ending in the capillaries, which 

 latter thus constitute the peripherica! medium of communication between 

 the arteries and the veins. The blood proceeds from the heart through the 

 arteries to the capillaries, where it undergoes certain changes; passing into 

 the veins from these, it again reaches the heart, thus performing a round 

 known as the circulation of the blood. The nutritious particles of the blood 

 pass through the thin walls of the capillaries into tlie various tissues, for the 

 sake of supplying the wear and tear of animal life ; the dead or effete por- 

 tions are taken up in the state of lymph by another set of vessels called 

 lymphatics, which discharge their contents into the veins, ultimately to be 

 subjected to certain influences which prepare them for again playing their 

 part in the general circulation. The chyliferous system is closely allied to 

 the lymphatic. This consists of excessively minute canals, which extend 

 from the intestines to the thoracic duct, and are called lacteals, on account 

 of their white appearance when distended with the milk-like chyle. 

 782 



