17 



THE PHYLOGENY OF THE FUNGI 



IT IS a commonly accepted axiom that evolution in both plants and 

 animals generally proceeds from the simpler to the more complex 

 structures, although it is recognized that in many cases a retrogression 

 from complex to simpler structures may occur. Therefore it is natural 

 that from the time that the ideas of evolution began to be given considera- 

 tion in the attempts to develop taxonomy along supposed phylogenetic 

 lines search was made for simple organisms as the probable primitive 

 types from which the complex phylogenetic trees of plants and animals 

 had developed. 



Since animals lack the power of synthesizing organic food stuffs out of 

 inorganic materials it has usually been assumed that the predecessors of 

 the animal kingdom must have been organisms that did possess that 

 power. The same assumption is necessary for the establishment of a 

 logical phylogenetic arrangement of the fungi and other more or less 

 plant-like organisms that are not autotrophic. There are a number of 

 groups of microscopic organisms ordinarily classed among the Bacteria in 

 which the energy necessary for the synthesis of organic materials is ob- 

 tained by various types of chemical reaction independent of light. Thus 

 the sulphur bacteria by the oxidation of sulphur or of HoS are able to gain 

 the necessary energy for their life processes. The same is true of those 

 bacteria which oxidize iron. There are several other types of energy- 

 obtaining processes. It is, however, only in those plants which develop 

 chlorophyll-like substances able to react with light to ol:)tain the energy 

 necessary for synthesis that a comparatively large amount of energy 

 became available and that production of large amounts of food occurred. 

 Probably not until then did the evolution of larger, more complex organ- 

 isms begin and not till then was the available food supply great enough to 

 permit the extended evolution of the various orders of animals and of 



fungi. 



From the fact that most of the simpler animals, green plants, and 

 fungi for the major portion of their life cycle consist of single, uninucleate 



628 



