394 PRINCIPLES OF ANIMAL BIOLOGY 



Oviparous (o vij/ a ran). Egg-laying. 



Oviposition (o' vi po zish' un). The laying of eggs. 



Ovisac (o' vi m.k). A chamber for the storage of eggs, being in some cases a lateral 

 pouch of the oviduct, as in the earthworm. 



Ovoviviparity {o' vo viv' i par' i ti) . The condition of being ovoviviparous. 



Ovoviviparous {o' voviirip' arus). Producing young from eggs that are retained in 

 the oviduct during their development, but without attachment to the oviduct, and 

 wholly from nutrition stored in the egg. 



Ovum (o' vimi) . An egg ; a relatively large passive cell which, in preparation for repro- 

 duction, has undergone one or two maturation divisions. 



Oxidation {oks' i da' shun) . The chemical process of combining with oxygen. 



Oxyhemoglobin (oks' i he' mo glo' bin) . Hemoglobin in combination with a certain 

 amount of oxygen. 



Oxytricha {oks it' ri ka). A genus of ciliated Protozoa. 



Paedogenesis (pe' do jen' e sis) . Sexual maturity in an animal otherwise immature; 

 the capability possessed by some species of reproducing while in the larval condi- 

 tion. 



Palaeomastodon {pa' le o mas' to don) . A genus of extinct animals belonging to the 

 elephant ancestry, found in the Oligocene of Egypt and India. 



Paleobotany (pa' le o hot' a ni). The paleontology of plants. 



Paleontology {pa' le on tol' oji). The science which treats of prehistoric life on the 



earth, now represented by fossils. 

 Paleozoic {pa' le o zo' ik). Pertaining to the geological era prior to the Mesozoic, when 



Amphibia, fishes, and the higher invertebrates were the dominant forms. 



Paleozoology {pa' le o zo oV oji). The science which deals with prehistoric animals. 

 Palinurus {paV i nu' rus) . A genus of crayfishes. 

 Palmitic {pal mit' ik). One of the very common fatty acids. 



Pancreas {pan' kreas). A gland which secretes a fluid containing several digestive 

 enzymes and discharges into the intestine. 



Pandorina {pan' do ri' no). A genus of colonial flagellate organisms in which the cells 



are held in a spheroidal jelly-like mass. P. morum (mo' rum) is one of the species. 

 Pangenesis {panjen' e sis). The theory that cells of an animal give off minute bodies 



which collect in the germ cells and later insure inheritance of parental qualities. 

 Panorpa {pa nor' pa). A genus of insects including certain scorpion-flies. 

 Papilio {pa pil' i o). A genus of butterflies; the swallow-tails. 

 Paramecium {par' a me' shi um). A genus of ciliated Protozoa. 

 Paramylum {par am' i luni). A substance related to starch, produced by certain 



green organisms. 

 Parapodium {par' a po' di um). A fleshy lateral protrusion on the segments of some 



worms; it bears the setse. 

 Parasite {par' a site). An animal which lives in or on another species of animal 



(its host), at the expense of the latter. 

 Parasitism {par' a si tiz'm). The condition of being a parasite. 

 Parathyroid {par' a thi' roid). One of several small glandular bodies associated 



with the thyroid. 

 Parenchyma {pa reng' ki ma). A loose spongy tissue found in certain low animals. 



