H2 NOT ALTOGETHER ABOUT PLANTS 



" low " on the other side. A region of the solvent in 

 which the solute is less abundant than in another region 

 has a lower osmotic pressure than that other region, and 

 osmotic movement sets up from the region of higher pres- 

 sure (more of the solute) to the region of lower pressure 

 (less of the solute). (This is suggestive of the way in which 

 movements of the air are from regions of high pressure 

 to regions of low pressure, a matter with which you are 

 probably familiar if you have studied physiography.) 



Having these facts in mind, you can probably under- 

 stand the statement that the movement of solutes in 

 plants " is from regions of high to regions of low pressure 

 and may be downward toward the roots, outward toward 

 the branches, or upward toward the flowers and fruits." 

 (Cowles's Ecology.) It is important that you should have a 

 true picture of this matter in mind, for osmotic movements 

 are of primary importance in the life of plants. In fact, 

 it is fair to say that what is accomplished by osmosis in 

 plants is similar and of equal importance to what is accom- 

 plished by the circulation of the blood in us. Though the 

 results of these two processes are similar, the processes 

 themselves are, of course, by no means alike; they are 

 very different indeed. 



37. Forms of Energy. — Energy is the power to do work. 

 You have energy. So has the falling stream of water. 

 So has wind. Wind mills show the power of moving air to 

 do work. Water wheels show the power of moving water to 

 do work. Motion is one of the forms of energy. As matter 

 exists in various states, so energy exists in various forms. 



Energy may also exist without being in the act of doing 

 work. Such energy is called latent, which means that 



