GLOSSARY 575 



otocyst (o'tSsIst). An organ supposed to be one of hearing found in many 



invertebrates. 

 ovary (5' va rl). An organ which produces egg cells; adj., ovarian (6 va' rl an), 

 oviduct (o'vidukt). The duct leading from the ovary either to the outside of the 



body or to a cavity opening externally. 

 oviparity (5 vi pSr' I ti). The condition which involves the laying of eggs; adj., 



oviparous (6 vIp' ii r&s). 

 ovipositor (o vl p6z' I tor). An organ which functions in the deposition of eggs, 



especially in insects. 

 ovo (o' vo). L.; egg. 

 ovoviviparity (o v6 viv I pSr' I tl). The condition which involves the laying of an 



egg that contains a living embryo. 

 ovum. An egg cell; also an egg, including the egg cell and its protective coverings. 

 Owen, Richard. English zoologist; 1804-1892. 

 oxidase (ok' si das). An enzyme which promotes oxidation, 

 oxidation (ok si da' shiin). A chemical reaction involving the addition of oxygen in 



chemical combination. 



Pale-, palae- (pa' le). G.; old, ancient. 



palpus {phV piis). An appendage, particularly in an arthropod, bearing organs for 



touch and taste; adj., palpal, 

 pancreas (pan' kre fls). A gland in vertebrates producing a variety of digestive 



secretions which are passed into the small intestine; adj., pancreatic (pin kre- 



at' Ik). 

 papilla (papil'a). A small nipple-like projection, either from a surface or of one 



tissue into another; a papilla may contain a sense organ, 

 para- (pftr' a). G.; beside. 

 parasite (par' a sit). An animal which lives in or upon another animal, to the injury 



of the latter but normally without causing its death. The phenomenon is 



parasitism (par' a sit iz'm), and the adj., parasitic (pftr a sit' Ik). 

 parenchyma (pa ren' ki ma). A loose mesodermal tissue contained in the bodies of 



some lower invertebrates, or the essential tissue which forms the mass of an organ. 

 Parker, George H. American zoologist, at Harvard University; 1864- . 

 parthen (par' then). G.; virgin, 

 parthenogenesis (par the no jen' e sis). The production of an offspring from an 



unfertilized egg cell; adj., parthenogenetic (par the no j6n 6t' Ik). 

 Pasteur (pas tur'), Louis. French chemist, 1822-1895. 

 pathogenic (path 6 jen' Ik). Disease-producing. 



pectoral (pek' to ral). Pertaining to the region of the body opposite the fore limbs, 

 ped (pfd). L.; foot. Pedal (pe' dal). Pertaining to the foot. 

 pedo-, paedo- (pe' do). G.; child. 



pedogenesis (pe do jen' e sis). The production of young by an immature animal, 

 pelagic (pe laj' Ik). Pertaining to the open water in an aquatic environment. 

 pelvic (pel' vik). Pertaining to the region of the vertebrate bodj' opposite the hind 



limbs; a bone or bones in this region articulating with the vertebral column and 



giving attachment to the hind limbs forms a pelvis (pM' vis). 

 penis (pe' nis). A male copulatory organ. 

 pepsin (pep' sin). An enzyme produced in the stomachs of vertebrates which 



changes proteins to peptones. ^ 



peri- (per' I). G.; around. 



pericardium (p6r I kar' dl lim). A coelomic or hemocoelic cavity in many inverte- 

 brates containing the heart; in vertebrates, a membranous sac inclosing a cavity 



which contains the heart; adj., pericardial. 



