396 PRINCIPLES OF ANIMAL BIOLOGY 



Primate. A mammal of the order including man and the apelike animals. 



Priority, law of. The rule that the name first given a species along with a description 



is the one that shall be accepted when different names have been applied to the 



same species. 

 Proboscis {pro bos' sis). The trunk of an elephant, consisting of the elongated nose 



and upper lip. Also a fleshy projection of other sorts. 

 Procoelous {piv see' lus). Having the anterior end of the centrum concave, the 



posterior end convex; said of vertebrae. 

 Procyon (pro' si on). The genus of Carnivora to which the raccoon belongs. 

 Proglottis (pi., proglottides, pro glot' ti deez). One of the individuals in a chain of a 



tapeworm. 

 Prophase. Any early stage of mitotic cell division, prior to the equatorial plate. 

 Prosecretin (pro' se kre' tin). A substance in the walls of the small intestine from 



which secretin is produced. 

 Prostomium. A rounded projection overhanging the mouth of an earthworm. 

 Protein. One of many organic substances, compounds of amino acids, which therefore 



contain carbon, hydrogen, nitrogen, and oxygen and often other elements. The 



molecules are large and very complex. Lean meat and egg albumen contain 



quantities of proteins. 

 Proterospongia haeckeli {pro' ter o spun' ji a hek' el i). A species of protozoon which 



forms gregaloid colonies. 

 Proterozoic. Belonging to the era preceding the Paleozoic. 

 Proteus. A genus of salamanders. 

 Prothrombase. A substance from which an enzyme of clotting (of blood) is 



produced. 

 Proton, A particle bearing a positive electric charge entering into the composition 



of the nuclei of atoms. 

 Protonephridium. A primitive excretory organ consisting of flame cells and con- 

 necting tubes. « 

 Protoplasm. The living matter of which animals and plants are essentially composed. 

 Prototheria. A subclass of Mammalia, including the egg-laying mammals such as 



the duckbill Ornithorhynchus and the spiny anteater Ecliidna. 

 Protozoa. One-celled animals. The phylum comprising the one-celled animals, 



including colonial forms in which the cells of the colony are, at least potentially, 



all alike. 

 Protozoology. The zoology of the protozoa. 



Pseudemys (su' de mis). A genus of turtles of the family Testudinidae. 

 Pseudopodium (su' do po' di U7n) (pi., pseudopodia). A blunt Hngerlike projection 



thrust out by Amoeba and other rhizopods. 

 Ptarmigan (tar' mi gan). Any one of several species of birds related to the grouse 



and partridges. 

 Ptyalin (ti' a lin). The starch-digesting enzyme of the saliva. 

 Pubis (pL, pubes, pu' hc.ez). The anterior one of two ventrally ])la('(Hl bones in the 



pelvic girdle of vertebrate animals abovi; th(> fishes. 

 Pulmonary circulation. The circiUation of the blood through the lungs, as distin- 

 guished I'roiii that, through the body in general (syst(>niic). 

 Pulsating vacuole. Same as contractile vacuole. 



Pupa. A quiescent stage in lh(> development of an insect, just before the adult con- 

 dition is reached. 

 Purkinje, Jan Evangelista (poor keen' ya). Bolicniian physiologist in the University 



of Prague, 1 787-1 Xf)9. 

 Pus. A collection of white cells at a wound or i)lace of infection. 



