CHAPTER XV. 



SOME OTHER WAYS IN WHICH CERTAIN PLANTS 

 OBTAIN FOOD. 



(This chapter is for reading, or the teacher may make demon- 

 strations before the class if there is time.) 



154. Nutrition of moulds.-^Start some growths of the black 

 mould as described in paragraph 49. Then for several days 

 observe the growth. First there appear small spots of delicate 

 white threads. This tuft of threads increases in size, the threads 

 elongate and branch. Finally upright threads appear which 

 bear the black heads (sporangia, sing, sporangium) and spores 

 again. Break the potatoes open through several of these tufts. 

 The threads of the mould enter the potato also. The mycelium 

 in the potato or in the bread absorbs food solutions from these 

 substances in the same way that root hairs absorb food solu- 

 tions. The potato and the bread are largely made up of starch 

 from green plants. This demonstration serves excellently to 

 show how the fungi which lack chlorophyll obtain their carbo- 

 hydrate food from the products of green plants (see paragraph 



147). 



155. Nutrition of the larger fungi. If we select some one 

 of the larger fungi, the majority of which belong to the mush- 

 room family and its relatives, which is growing on a decaying 

 log or in the soil, we shall see on tearing open the log, or on 

 removing the bark or part of the soil, as the case may be, that 

 the stem of the plant, if it have one, is connected with whitish 

 strands. During the spring, summer, or autumn months, 

 examples of the mushrooms connected with- these strands may 

 usually be found readily in the fields or woods, but during the 



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