PRO 



PRO 



former of these terms was applied by the 

 older botanists to the branch laid down 

 in the process of layering. The latter 

 denotes an offset in certain plants. 



PROPERTIES OF BODIES. The 

 physical properties are divided into the 

 essentiat, or principal ; viz. extension and 

 impenetrability, which are common to 

 all bodies, and indispensable to their ex- 

 istence ; and the non- essential, or acces- 

 sory, as compressibility, expansibility, 

 porosity, divisibility, elasticity, and gra- 

 vity. 



PROPERTY. In Logic, this term 

 denotes a predicable which expresses 

 something essentially conjoined to the 

 essence of the species. It is thus dis- 

 tinguished from the logical accident, 

 which denotes something contingently 

 joined to the essence. Thus, redness is 

 a property of blood, but an accident of a 

 house. 



PROPO'RTION. This term denotes 

 t\ie portions, or parts, of one magnitude 

 which are contained in another. In the 

 language of Mathematics, the term has 

 been appropriated to express the equality 

 of ratios ; or, as it may be less minutely 

 explained, the case in which one magni- 

 tude is as many times greater or less 

 than another, as a third magnitude is 

 greater or less than a fourth. See Ratio. 



PROPOSITION {propono, to propose). 

 A short discourse, in which a geometrical 

 truth is stated and considered •, it being 

 thereby proposed either to demonstrate 

 something which is asserted, in which 

 case the proposition is called a theorem ; 

 or to show the manner of doing some- 

 thing which is required to be done, in 

 which case the proposition is called a 

 problem. 



A logical proposition is "a sentence 

 indicative;" in other words, a sentence 

 which affirms or denies. A proposition 

 is distinguished, with reference to its 

 substance, as categorical, when it ex- 

 presses anything absolutely, as " Caesar 

 deserved death ;" hypothetical, when it 

 expresses any thing under a hypothesis, 

 as, " If Csesar was a tyrant, he deserved 

 death." Categorical propositions are 

 termed pure, when they assert simply or 

 purely, that the subject does or does not 

 agree with the predicate ; and modal, 

 when they denote in what mode or man- 

 ner it agrees. Thus, " Brutus killed 

 Caesar," is a pure categorical proposition ; 

 while, " Brutus killed Caesar justly," is 

 modal. 



PROSE'NCHYMA. A term applied 

 274 



by Link to that form of parenchyma in 

 plants, in which the cells taper to each 

 end, and overlap each other; the term 

 parenchyma being restricted to that form 

 of the tissue, in which the cells have 

 truncated extremities. 



PROTEIN (TTpwreuft), to hold the first 

 place). The name given by Mulder to 

 the precipitate obtained by adding acetic 

 acid to a solution of caustic potash, con- 

 taining fibrin, albumen or gelatine, ani- 

 mal or vegetable, in solution. 



PRO'TEOLITE. Under this term and 

 that of Cornubianite, Dr. Boase describes 

 the rock in contact with granite, which 

 has been called argillaceous schist, or 

 clay-slate, greywack6, or killas. The 

 proteolite is of a lighter colour than the 

 cornubianite, soft, arenaceous, and slaty. 

 They appear to be chiefly composed of 

 compact felspar, with quartz, mica, and 

 schorl, and contain beds of that sub- 

 stance and of quartz. 



PROTHO'RAX. The first of the 

 three segments which constitute the 

 thorax in insects. 



PROTO- (TrpwTop, the first). This pre- 

 fix denotes, in Chemistry, the lowest de- 

 gree in which one body unites with an- 

 other, as prof-oxide. Per denotes the 

 highest degree, as per-oxide. 



PRO'TOGENE. Talcose Granite. A 

 mixture of felspar, quartz, and talc or 

 chlorite. It occurs abundantly in the 

 Alps of Savoy, and is found in Cornwall, 

 where, on decomposition, it yields the 

 china-clay or porcelain-earth, which is 

 annually exported in large quantities. 



PROTOZO'A (TrpwTov, first, ^mov, an 

 animal). A designation of one of the 

 primary divisions of the Animal King- 

 dom, from their constituting the first 

 step of animal organization. They cor- 

 respond with the Acrita of Macleay, with 

 the Cryptoneura of Rudolphi, and with 

 the Oozoa of other witers. 



PROTOZO'TC SYSTEM (TrpaJTov, first, 

 ^wov, an animal). A geological term, ap- 

 plied to the lowest system of rocks in 

 which the traces of any organic structure 

 have been discovered. It is the system 

 next in ascending order to the hypozoic. 



PROXIMATE PRINCIPLE. A term 

 applied, in analyzing any body, to the 

 principle which is nearest to the natural 

 constitution of the body, and more im- 

 mediately the object of sense, as distin- 

 guished from intermediate or ultimate 

 principles. Ultimate principles are the 

 elements of which proximate principles 

 are composed. 



