CHAPTER I. 



SOflE PLANTS THAT LEAD EASY LIVES. 



The aim of this chapter is to set children to thinking of plants as 

 living, growing things requiring food and subject to dangers. In the 

 study of the most elementary principles of plant physiology a clear 

 conception of the cell, chlorophyll and protoplasm is helpful, and 

 these ideas are more easily gained from lower than from higher plants. 

 The cell of the water net, even without the microscope, is a definite, 

 tangible object. All green Algae are excellent for illustrating the 

 giving off of oxygen, and the marine Algee tell a very striking slory 

 of the adaptation of plants to their surroundings. So Algee have 

 been chosen to illustrate this chapter, in spite of the fact that many 

 teachers are not familiar with them and will naturally be reluctant 

 to use them. But, since in this case neither great knowledge of minute 

 structure nor special skill in manipulation is required, it is earnestly 

 hoped that children will be encouraged to bring material to illustrate 

 this lesson. 



Hydrodictyon, or water net, is the most attractive of the fresh 

 water Algae if a microscope is not available, and it is very abundant, 

 in Southern California at least. As noted in the Reader, the larger 

 nets are usually found much broken up, but smaller entire ones are 

 pretty sure to be entangled with them. The children, in searching 

 for them should use small quantities, examining them in the water, 

 either in white dishes or in thin glass jars in a good light. 



For the study of the cell the coarsest pieces of net should be used. 

 The term meshes is applied to the spaces enclosed by the four to seven 

 sides. The teacher should make sure that the children understand 

 that each one of these sides is a cell. The term cell is so misleading 

 that beginners are likely to apply it to the meshes instead. The cells 

 of the water net are usually large and clearly defined, so that with 

 only a hand lens and the pictures, children can gain a tolerably clear 

 notion of their nature, but they will be much more impressed by 

 seeing them under a low power of a compound microscope. They 



