GLOSSARY 521 



Ovoviviparous (6 v6 vi vip'a ids), a condition of retention of the. egg in the 

 mother's body where It is nourished by the yolk of the egg. 



Ovulation (o vu la'shun), the process of discharging mature eggs from the ovary. 



Oxidation (ok si da'shiin), a chemical combination of oxygen with another 

 element. 



Paleozoology (pale 6 z6 ol'o ji), the science that treats of the animals of the 



past as represented by fossil remains. 

 Parasite (par'asit), an organism that lives on or within and at the expense of 



another organism. 

 Parenchyma (pa reng'ki ma). (See Mesenchyme.) 

 Parietal (pa ri'e tal), pertaining to the walls of the coelom. 

 Parthenogenesis (par the no jen'e sis), the development of an egg without 



fertilization. 

 Pathology (pathol'oji), the study of abnormal structures and abnormal func- 

 tioning of life processes. 

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

 Pedicellaria (ped i se la'ri a), pincherlike structures found over the surfaces of 



sea urchins and starfishes. 

 Peduncle (pedung'kl), the stemlike attachment of certain shells and barnacles 



to other objects. 

 Pelagic (pelaj'ik), floating near the surface of water. 

 Pericardial (peri kar'di al), situated around the heart. 

 Periosteum (per i os'te um), the membranous covering of bone. 

 Peripheral nervous system (pe rif'er al), that part of the nervous system ex- 

 clusive of the brain and spinal cord. 

 Peristaltic (per i stfil'tik), forcing the food along the intestine by rhythmical 



contractions of the intestinal wall. 

 Peritoneum (per i to ne'um), the membrane that lines the coelom of vertebrates. 

 Phagocyte (fag'osit), a white corpuscle which engulfs and destroys bacteria 



and other foreign material. 

 Pharynx (far'ingks), the region between the mouth and the esophagus. 

 Pharyngeal (fa rin'je al), pertaining to the pharynx. 

 Phenotype (fe'no tip), a type of organism possessing a complex of characters 



in its external features. 

 Phenotypic (fe no tip'ik), pertaining to phenotype.' 



Photosynthesis (fo to sin'the sis), the process by which green plants manufac- 

 ture starch from raw materials. 

 Phototropism (fo tot'ro piz'm), response of an organism to light. 

 Phylogeny (filoj'eni), the study of the origin and relationships of the different 



groups and races of organisms. 

 Physiology (fiz i ol'o ji), the study of the function of the parts of an organism 



as well as its living processes as a whole. 

 Pia mater (pi'ama'ter), the membrane which is the immediate covering of the 



brain and spinal cord. 

 Pilidium (pilid'ium), helmet-shaped larva of certain forms. 

 Pineal (pin'e al) body, a dorsal projection from the diencephalon and thought 



to be the vestige of a third or me'dian eye in vertebrates. 

 Pituitary (pi tu'i ter i) body, a glandular structure attached to the neutral side 



of the diencephalon of the vertebrate brain. It is an endocrine organ. 

 Placenta (plasen'ta), the vascular membrane which connects the embryo with 



the parent. 

 Placula (plak'ula), a type of blastula in which the animal and vegetative halves 



are somewhat compressed toward each other. 

 Plankton (plangk'ton), the small pelagic organisms which are at the mercy of 



the waves. 

 Plasma (plaz'ma), the fluid portion of the blood. 



Plasmagel (plaz'ma jel), the viscous 'or semisolid portion of protoplasm. 

 Plasmasol (plaz'ma sol), the more fluid phase of protoplasm. 



