CHAPTER XXII. 



CLASSIFICATION OF THE FUNGI. 



429. Classification of the fungi. Those who believe that the fungi repre- 

 sent a natural group of plants arrange them in three large series related to 

 each other somewhat as follows-. 



The Basidium Type or Series. 

 The number of gonidia on a ba- 

 sidium is limited and definite, 

 and the basidium is a characteris- 

 tic structure; examples: uredineae 

 (rusts), mushrooms, etc. 



The Ascus Type or Series. The 

 number of spores in an ascus is 

 limited and definite, and the ascus is 

 a characteristic structure; examples: 

 leaf curl of peach (exoascus), pow- 

 dery mildews, black knot of plum, 

 black rot of grapes, etc. 



430. Others believe that the fungi do not represent a natural group, but 

 that they have developed off from different groups of the alga? by becoming 

 parasitic. As parasites they no longer needed chlorophyll, and conse- 

 quently lost it. 



According to this view the lower fungi have developed off from the lower 

 algae (saprolegnias, mucors, peronosporas, etc., being developed off from 

 siphonaceous algae like vaucheria), and the higher fungi being developed 

 off from the higher algae (the ascomycetes perhaps from the Rhodophyceae). 



431. A very general outline of classification,* according to the former of 



The Gonidium Type or Series. 

 The number of gonidia in the spo- 

 rangium is indefinite and variable. 

 It may be very large or very small, 

 or even only one in a sporangium. 

 To this series belong the lower 

 fungi; examples: mucor, saprolegnia, 

 peronospora, etc. 



* Class Myxomycetes, or Mycetozoa. To this class belong the "slime 

 molds," low organisms consisting of masses of naked protoplasm which 

 flows among decaying leaves and in decaying wood, coming to the surface 

 to fruit. The fruit in many cases resembles miniature puff-balls, and these 

 plants were formerly classed with the puff-balls. The spores germinate by 



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