FUNGI : BASIDIUM FUNGI 303 



471. Two theories of the evolution of the fungi. There 

 are two theories of the evolution of the fungi. The first theory is 

 that the fungi have had their origin at different points from the 

 algae, i.e., certain groups of fungi being developed off from cer- 

 tain groups of algae as suggested above. The second theory is 

 that the fungi represent a natural group of plants, and that this 

 group has followed a line of development of its own, the higher 

 forms being developed from the lower, just as it is believed that 

 the higher algae have developed from the lower. There are a 

 number of reasons for holding this theory. One of the foremost 

 of these reasons is, that there are, within each of the three classes, 

 such manifest evidences of lines of evolution tending to show 

 that the higher forms of each group have had their origin among 

 lower members of the same group. The resemblances to the 

 algae may be accidental; they may represent cases of parallel 

 evolution, which it is generally believed has occurred both in 

 certain groups of plants and animals. While these resemblances 

 are strong in some points, there are still connected with them 

 certain structures and processes, which are not present in the 

 algae. We probably can never decide which theory is the cor- 

 rect one. These theories may continue to exist side by side as 

 interesting topics for speculation. . The author does not commit 

 himself wholly to either. But it is generally accepted that, in 

 the study and classification of the fungi and algae, it is more con- 

 venient to arrange the classification according to the second 

 theory. 



