FLOWERLESS PLANTS 443 



Thus we see in a general way that the fungi reduce dead nitroge- 

 nous matter to soluble plant food in the soil. Leaves, twigs, and 

 wood decay to form vegetable mould and animal matters ; manures 

 and composts must be thoroughly rotted before they become available 

 for plant foods. 



A smaller group of fungi live as parasites upon or within plants 

 and animals, and thus cause the majority of those diseases commonly 

 known as contagious or infectious. We should know something 

 about these and how they may be controlled, and to this end we 

 may describe a few that commonly attack garden plants and trees, as 

 well as some that are of great importance in relation to home and 

 school sanitation. 



Finally, a small group of bacteria are truly symbiotic and live 

 within the roots of plants, especially of the clovers and peas, and 

 possess the power of absorbing nitrogen from the air and of fixing it 

 in soluble form as food for the plants. As with the lichen and the 

 algae, the root supplies moisture and support, while the microbe manu- 

 factures plant food in return. It has long been known that clover, 

 for example, enriches the soil in which it grows, and this fact is now, 

 in a measure, explained. 



The above facts are given to aid the teacher in planning the les- 

 sons and in appreciating the value of the observations and experiments 

 that follow. 



Mushrooms. — The best time during the school year to 

 study mushrooms is in the fall, after a spell of wet weather. 

 We may begin by asking the class how many know mush- 

 rooms and have found them growing in the neighborhood. 

 The children may know them better by the popular name 

 "toadstools," which is commonly used to designate poi- 

 sonous or worthless mushrooms ; but, since this is not a 

 helpful term, we had better make the distinction by calling 

 them "poisonous mushrooms " instead. Possibly one of the 

 class knows some one who is raising mushrooms and can 

 tell the rest how it is done. Ask the children each to dig 



