PRIMER OF PRIMERS. 179 



sudden changes in the temperature of the air, and 

 thus tends to increase the number and severity of 

 hail-storms. 



5. Because the presence of the forest tends to 

 prevent the occurrence of early frosts in the 

 neighboring agricultural districts. 



6. Because the presence of the forest insures a 

 greater uniformity in the relative quantity of 

 moisture in the air at different seasons of the year. 



All life, whether animal or plant, has its begin- 

 nings in a minute germ-cell containing a nucleus 

 surrounded by a transparent substance called pro- 

 toplasm. 



Although cases exist where plants appear with- 

 out the apparent sowing of seed, yet, in all such 

 cases, seeds or germs must have been present. 



The conditions necessary for plant-growth, named 

 in the order of their importance, are : 



1. The germ or seed. 



2. The sunshine and the heatshine. 



3. The nourishment, or the food the plant re- 

 quires for its growth. 



4. The cradle, or the soil in which the plant is 

 born. 



When a particular species of plant life is to be 

 maintained, the character of the soil is of the 



