V. 



THE FUNGI. 



The Fungi include a very large number of chlorophyl- 

 less saprophytic or parasitic plants. A saprophytic plant 

 is one that lives by the absorption of decaying organic 

 matter ; a parasite lives on other living organisms, robbing 

 them of the nourishment they have prepared for them- 

 selves. In some cases the same organisms may live either 

 as saprophytes or parasites. Some of the Fungi are organ- 

 isms of very low development ; in others the development 

 has reached a considerable degree of complication. In the 

 higher forms the development of mycelial rhizoids is 

 marked ; these are the fine threads of the mycelium of the 

 plant which permeate the substratum on which the plant 

 grows and absorb from it nutrient materials; in many 

 cases this mycelium acts as a ferment on the substances in 

 the soil, causing their decomposition and preparing them 

 to become food for the plant. There is in no case a tend- 

 ency to the formation of leaves. The most striking char- 

 acteristic of these plants is the absence of chlorophyl ; this 

 fact alone, however, does not determine their separation 

 into a subdivision by themselves. That separation is based 

 rather upon morphological characteristics. The plant 

 body is a thallus that develops by apical growth into root 

 hyphce, the mycelium, or branches below the surface of the 

 substratum on which the plant grows, and shoot hyphce, or 

 branches above the surface. A few forms that do not 

 develop by apical growth, such as the yeast plants, for 

 example, are classed as Fungi on account of resemblances 



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