54 FIRST YEAR COURSE IN GENERAL SCIENCE 



Tenacity, ability to resist being pulled apart. A steel 

 cable bears a great strain without breaking. 



Brittleness, capability of breaking under a sudden blow or 

 shock. Glass is a substance having brittleness. 



Elasticity, capability of regaining its shape and volume 

 after the force which changes the form is removed. A 

 rubber ball which has been flattened becomes round again. 



Flexibility, capability of bending without breaking. A 

 rope is flexible. 



The terms elasticity and flexibility are sometimes confused. 

 Rubber is flexible it will bend; it is also elastic, for it 

 unbends when the bending force is removed. A piece of 

 lead is flexible it will bend; but it is not very elastic, for 

 it remains bent when the bending force is removed. 



These properties, and many others, are physical proper- 

 ties. 



53. Properties of Living Matter. There are four special 

 properties which belong to all living matter and do not 

 belong to any forms of non-living matter. The properties 

 or characteristics of living matter are called physiological 

 properties. There are four physiological properties: 



Irritability, the property of responding to influences from 

 without. The tips of plant roots grow toward water. 



Spontaneous motion, power to change the position of the 

 body or a part of the body. Stems twine around a support; 

 a snake glides along the ground. 



Nutrition, the property of taking up certain substances to 

 be used in constructing the body. Proper food and air are 

 all that is necessary to make a chicken grow to be a fowl of 

 twenty times its original weight. 



Reproduction, the power to form other bodies like them- 

 selves. Plants form seeds and animals form eggs, from 

 which grow new bodies like themselves. 



54. Organisms. Bodies having physiological properties 

 are called organisms, and much of the matter of which they 



