CHARACTERISTICS OF THE TRUE EUNGI 49 



have been ascribed by Eriksson to the presence of the protoplasm of 

 the rusl mixed with the protoplasm of the host. To this included 

 fungous protoplasm he gave the name mycoplasm. 



Some fungi are symbiotic, that is, they are found in intimate re- 

 lation with chlorophyll-containing plants and obtain from them food 

 of a carbonaceous character, but without apparently injuring the 

 green symbiont. When they live with a^gae, they commonly form 

 lichens; or if in connection with the roots of trees, orchids; and in 

 prothallia they form what is known as mycorhiza (Fig. 16). 



The spores or reproductive cells of fungi may be of two kinds: 

 non-sexual spores and sexual spores. The non-sexual spores are cells 

 which are formed vegetatively. They are cells which take special 



Fig. 16. — Ectotrophic mycorhizas. At left hyphal mantle on root of hickory 

 Carya ovata in cross section; at right root tip of an oak, Quercus, with fungous mantle. 

 (From Gager. after W. B. McDougall.) 



forms in the different groups of fungi and are produced as special cells 

 in a purely vegetative manner. They represent a special part of the 

 thallus given over to reproduction. Upon the formation of these 

 spores, which may germinate at once or live for some time as resting 

 spores, the rapid multiplication of the fungi depends. It is the innu- 

 merable quantity of these non-sexual spores upon which an epidemic 

 of some particular fungous disease may depend. Only the most general 

 characters of the various kinds of spores can be discussed in an intro- 

 duction of this kind. The special kinds will receive due attention as 

 we proceed. Spores which are cut off, or pinched off, in concatenation 

 from the end of a vertical hypha, are known as conidiospores. In the 

 rusts such conidiospores become uredospares, and in the mushrooms 

 basidiospares. Where the non-sexual spores are formed in a spore case, 

 4 



