GLOSSARY 569 



Parasite (par'-a-sit), a living thing that lives in close association with some 

 other living thing, deriving its nourishment from its host, but not contribut- 

 ing anything to the welfare of the host. 

 Parasitism (par'-a-slt-izm), an association between two living organisms in 



which one benefits and the other is harmed by the association. 

 Pathogenic (path-o-jen'-Ik), disease producing. 

 Pectoral (pek -to-ral), pertaining to chest. 

 Pedal (ped'-al), pertaining to the feet. 

 Pedicellaria (ped-i-se-la'-ri-a), small pinchers found on the surface of many 



echinoderms. 

 Pedipalp (ped'-I-palp), a small, leg-like appendage near the mouth of spiders. 

 Pelagic (pe-laj'-ik), pertaining to the open sea. 



Pellicle (pel'-i-kl), the outer covering of certain protozoa, such as Paramecium. 

 Pelvic (peT-vik), refers to the hip region. 

 Penis (pen'-is), a male reproductive organ used to transfer sperm to the body 



of the female. 

 Peri- (per'-i), prefix meaning "around". 

 Perimysium (per-i-mi'-shi-um), a tough transparent membrane surrounding a 



muscle, holding the fibers together. 

 Peristaltic (per-i-stal'-tik), referring to the method of movement of materials 

 through the alimentary tract and of the blood through vessels in annelid 

 worms. 

 Peritoneum (per-i-to-ne'-um), tissue that lines the coelom. 

 Phalanges (fa-lan'-jes), finger bones and toe bones. 

 Pharynx (far'-Ingks), a cavity connected to the mouth, usually just posterior to 



the mouth. 

 Phylogeny (fl-Ioj'-e-nl), the development of the race. 



Phylum (fi'-lum), pi. phyla, a major division of the plant or animal kingdoms. 

 Physiology (fiz-i-6l'-6-ji), a phase of biology dealing with the functioning of the 



living organism. 

 Pituitary (pi-tu'-i-tar-I), an endocrine gland found in the head. 

 Pituitrin (pi-tu'-i-trin), hormone produced by the posterior lobe of the pituitary 



gland. 

 Placenta (pla-sen'-ta), an outgrowth of the embryonic mammal that forms an 

 intimate attachment with the uterus of the mother and through which food, 

 oxygen, and wastes are exchanged. 

 Plankton (plangk'-ton), small organisms on the surface of bodies of water. 

 Plasma (plaz'-ma), the liquid part of the blood or lymph. 



Plasma membrane, the thin differentially permeable membrane that surrounds 

 the protoplasm of a cell, regulating the movements of materials into and 

 out of the cell. 

 Polyp (pSl'-ip), a stage in the life of coelenterates that somewhat resembles 



Hydra and is attached so that it cannot move from place to place. 

 Post- (post), prefix meaning "behind". 

 Pre- (pre), prefix meaning "in front of". 



Predaceous (pre-da'-shus), animals which feed or prey on other animals. 

 Pro- (pro), prefix meaning "first" or "before". 



Proboscis (pro-bos'-Is), an extension of the nose or mouth parts; may be the 

 nose, as in the elephant; the mouth, as in sucking insects; or the pharynx, 

 as in Planaria. 

 Proctodeum (prok'-to-de-um), embryonic invagination that forms the anus. 



