9 o NOT ALTOGETHER ABOUT PLANTS 



stance becomes dissolved in another. A substance which 

 will dissolve in another substance is said to be soluble in 

 that substance. Thus salt and sugar are soluble in water. 

 Many more substances are soluble in water than are 

 soluble in any other substance. This fact that it is the 

 greatest of dissolvers has much to do with the very impor- 

 tant relation of water to all living things, as you shall see. 



Solution, besides being the name of a process, is also 

 used to name that which results from the process. Thus, 

 solution occurs when sugar is put in tea, and that which 

 results is also called a solution. It is a solution of sugar 

 in tea. A solution is composed of two parts, the solvent 

 and the solute. In this case the tea is the solvent and 

 the sugar is the solute. The solute is the dissolved sub- 

 stance. The solvent is the substance in which the solute 

 is dissolved. There may be more than one solute in the 

 same solvent. Thus in the tea we have particles from the 

 tea leaves dissolved as well as particles of sugar. 



The law of solution is that particles of solutes tend to 

 become equally distributed throughout the solvent. The pro- 

 cess is not complete until such equal distribution has been 

 attained, until the particles of the solute or solutes have 

 become equally distributed through all parts of the solvent 

 which they can reach. So, until they have become equally 

 distributed, there is a force which seems to pull them 

 farther and farther apart, just as there is a force which 

 seems to pull a falling ball to the ground. 



Solution is of the utmost importance in life, both in plant 

 and animal life. Though living things appear to be solid 

 bodies, they are composed of cells whose contents are more 

 or less fluid, and practically all the processes of life occur 

 in that physical condition of matter which is called solution. 



