GLOSSARY 387 



Pi'ne-al body (Lat. pinea, a pine cone) : a glandlike body in the roof 

 of the third ventricle of the brain. 



Pin'na (Lat., a feather) : the folded sheet of cartilage which forms 

 the principal part of the external ear. 



Pithed : deprived of the central nervous system by the passing of a 

 wire or needle through the vertebral canal. 



Plas'ma (Lat. and Gr., anything formed or molded) : the colorless 

 fluid of the blood. 



Pleu'ra (Gr., a rib, the side) : the serous membrane which covers the 

 lungs and lines the cavity of the thorax. 



Plex'us (Lat., a twining, braid, from plectere, to braid, twine) : a net- 

 work of vessels, nerves, or fibers. 



Pons Va-ro'li-i (Lat., bridge of Varoli an Italian anatomist): a 

 band of nervous tissue on the front or ventral side of the medulla 

 oblongata, connecting the two sides of the cerebellum. 



Pop-lit'e-al (Lat. poples, the ham) : pertaining to the ham or back of 

 the knee, as the popliteal artery or ligament. . 



Por'tal circulation (Lat. porta, gate) : the passage of venous blood 

 from the capillaries of one organ to those of another before reach- 

 ing the heart. In man, the circulation of the liver. 



Portal vein : the large vein of the liver, bringing blood to its capil- 

 laries. 



Pos-te'ri-or (Lat., coming after) : away from the head, or sometimes, 

 in human physiology, toward the back. 



Po-tas'si-um (Lng. potash) : a chemical element, found only in com- 

 bination with acids. 



Prim'i-tive sheath : the inclosing membrane of a nerve fiber. 



Proc'ess (Lat. processus, a going forward) : an outgrowth ; a projec- 

 tion, as the spinous process of a vertebra. 



Pro'te-ids (Gr. protos, first) : the food elements which form tissue. 



Pro'to-plasm (Gr. protos, first, and plasma, anything formed) : an 

 albuminoid substance consisting of carbon, oxygen, nitrogen, and 

 hydrogen ; capable under proper conditions of manifesting certain 

 phenomena of life ; " the physical basis of life." 



Pty'a-lin (Gr. ptualon, spittle) : the peculiar principle of saliva which 

 acts as a ferment on starch, converting it into dextrose, a variety 

 of sugar. 



Pul'mo-na-ry (Lat. pulmo, a lung) : pertaining to the lungs, as the 

 pulmonary arteries, which carry blood from the heart to the 

 lungs. 



