Chapter VIII. 



Fungi. Kinds of Fungi. Algal Fungi. 



The fungi are undoubtedly descended from algal stock and, 

 as commonly understood, more than one line of descent is prob- 

 able. That is to say, the ancestors of the present day fungi 

 were all algae, though of at least several kinds. The algae com- 

 prise a group of plants which have in general a water-habit. A 

 great many fungi still retain this water-habit but unlike the 

 algae, which possess leaf-green, they are unable to manufacture 

 their own food. On the other hand, a vast number of fungi 

 have learned to live in the open air or in the tissues of other 

 plants or on the ground ; in short, have abandoned the aquatic 

 for some terrestrial habit. With this change in habit have gone 

 on changes in form and methods of reproduction. Botanists 

 recognize three great groups of fungi. The lowest group is 

 that of the algal fungi, including those of which the majority 

 have retained the aquatic habit and in which the reproductive 

 methods have been less strongly altered than in the two remain- 

 ing higher groups. The latter groups are in general terrestrial, 

 and have adopted two very distinct methods of reproduction. 

 In all of the sac fungi spores are formed inside of sacs and these 

 sacs in most forms are elongated cylinders containing eight 

 spores each. In the stalked fungi the spores are produced ex- 

 ternally on fungus threads, and are borne on fine and delicate 

 stalk threads. The number of such stalked spores on each 

 thread is commonly definite for any given species and the usual 

 number is four. The production of spores by breeding is 

 known to occur throughout the algal fungi and has been ob- 

 served in many cases among the sac fungi and probably occurs 

 throughout the latter group. Up to within recent times no 

 undisputed evidence had been produced of the presence of a 

 breeding act among the stalked fungi ; but it is now known that 



