286 GLOSSARY 



Nitrogen. A gas, N, comprising approximately four-fifths of the 



atmosphere. 

 Nutrient. Food; aliment. 

 Nutrition. The process of promoting and sustaining growth and work 



of animal and plant. 

 Nutritive ratio. The proportion between the proteids and other con- 

 stituents in a food. 452. 

 Optimum temperature. The best temperature for the performance of 



a certain function. 201, 321. 

 Organic. Pertaining to organisms, — that is, to animals and plants- 

 Organic matter has been elaborated or compounded of inorganic 

 materials, and exists in nature only as it is made by animals or 

 plants. Flesh, wood, starch, protoplasm, sugar, are examples. 

 The chemist defines organic matter as that which contains carbon 

 in combination with other elements. 25, 256, 32. 

 Ornithology. Science of birds. 



Osmosis. The movement of liqui Is thrcjugh membrane^. 1H4, 185. 

 Oxygen. A gas, O, comprising about one-fifth of the atmosphere. 

 Palatable. Of good or pleasant taste. 376,470. 

 Particles of soil. The ultimate or finest divisions of soil. 

 Pedigree. A recorded genealogy. 486. 

 Peptone. A diffusible and soluble compound formed from nitrogenous 



substances by the action of digestive liquids. 389, 390. 

 Perennial. A plant which lives three or more years. Rhubarb, apple 

 trees and Canada thistles are examples. [143. 



Pliosphnie. A substance containing or composed of phosphoric acid. 

 Photosynfhei is. Making of organic matter from CO, and water in pres- 

 ence ot light. 198, 199. 

 Physical. Pertaining to the body or structure of a thing, as dis 

 tinguished from its life or its spirit. Pertaining to the action of 

 inorganic forces, as heat, light, electricity, movement of water. 

 Physiology. The science of life-process or of functioning. It treats of 



organs, and their work and uses. 

 Potential. Possible ; latent. Said of powers which may be brought 



into action, but which are now dormant. 42o. 

 Precipitate. The sediment resulting from chemical action. S90a. 

 Prepotent, Said of animals which have the power of perpetuating their 



own characteristics to a striking degree. 483. 

 Protoplustyi. A very complex and changeable organic nitrogenous com- 

 pound, present in all living things, and necessary to their existence. 

 It is the living matter of cells. 



