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GLOSSARY 



Op'tic (Gr. optikos, sight). Pertaining to 



the eye or vision. 

 O'ral (L. OS, mouth). Pertaining to the 



mouth. 

 Or'bit (L. orbis, circle). The bony eye 



socket. 

 Or'gan (Gr. organon, an instrument). A 

 group of tissues associated to perform 

 one or more functions. 

 Or'gan-elle". A minute organ found in Pro- 

 tozoa. 

 Or-gan'ic com'pound (Gr. organon, an 

 implement; L. componere, to put to- 

 gether ) . A carbon-containing molecule. 

 Or'gan-ism (Fr. organisme). Any living 



thing. 

 Or'ga-nog"e-ny (Gr. organon, an instru- 

 ment, implement; genesis, birth). The 

 developmental processes involved in 

 the formation of specialized tissue and 

 organ systems. 

 Or'i-gin (L. orior, rise, become visible). 

 Part of the muscle attached to an im- 

 movable structure. 

 Or'tho-gen"e-sis (Gr. orthos, straight; gen- 

 esis, descent). Progressive evolution in 

 a given direction. 

 Os-mo'sis (Gr. osmos, pushing). Diffusion 

 through a semi-permeable membrane. 

 O'to-lith (Gr. oiis, ear; Uthos, stone). A 

 small calcareous mass found in the 

 auditory organ of many animals. 

 O'va-ry (L. ovarium, ovary). The primary 

 female sex gland in which the eggs are 

 formed. 

 O'vi-duct (L. ovum, egg; ducere, to lead). 

 The tube through which the eggs are 

 carried from the ovary to the uterus or 

 outside the body. 

 O-vip'a-rous (L. ovum, egg; pario, to pro- 

 duce). Producing eggs which hatch 

 outside the body. 

 0'vi-pos"i-tor (L. ovum, egg; ponere, to 

 place). An organ found in female in- 

 sects for depositing eggs. 

 0'vo-vi-vip"a-rous (L. ovum, egg; vivus, 

 alive; parere, to bear). Producing eggs 

 which hatch within the body. 



O-vu-la'tion (L. ovum, egg). The discharge 

 of the unimpregnated ovum from the 

 ovary. 



O'vum (L. egg). The mature female gam- 

 ete. 



Ox'i-da"tion (Gr. oxijs, acid). An increase 

 of positive charges on an atom, or the 

 loss of negative charges. 



Pae'do-gen"i-sis (Gr. pais, a child; genesis, 

 origin). Reproduction while in the im- 

 mature or larval stage. 



Pa'le-on-tor'o-gy (Gr. palaios, old; ons, be- 

 ing; logos, discourse). Study of fossils. 



Palp (L. palpare, to feel). One of the 

 pointed sense organs attached to the 

 mouth of some invertebrates. 



Pan'cre-as (Gr. pan, all; kreas, flesh). A 

 digestive gland located behind the 

 stomach and opening by a duct into 

 the duodenum. 



Par'a-site (Gr. para, beside; sitos, food; or 

 parasitos, eating beside another). An 

 organism which lives on or in another 

 living organism from which it receives 

 an advantage without compensation. 



Par'a-thy"roid (Gr. para, near; thijreoei- 

 des, shield-shaped). A small endocrine 

 gland located near the thyroid. 



Pa-ren'chy-ma (Gr. para, beside; enchtjma, 

 infusion). Loose, spongy connective 

 tissue. 



Pa-ri'e-tal (L. parietis, a wall). Pertaining 

 to the coelomic wall. 



Par'the-no-gen"e-sis (Gr. parthenos, virgin; 

 genesis, origin). Reproduction by de- 

 velopment of the egg without its being 

 fertilized by the male element. 

 Pa-ter'nal (L. paternus, from pater, father). 



Pertainincr to a father. 

 Path'o-gen"ic (Gr. pathos, suffering; gene- 

 sis, to produce). Disease-producing. 

 Pa-thoro-gy (Gr. pathos, disease; logos, 

 study). The study of abnormal struc- 

 tures and processes. 

 Ped'al (L. pes, foot). Pertaining to the foot 

 or feet. 



