WHAT ARE LICHENS ? 31 



If the organisms could in some way form an associa- 

 tion mutually beneficial they would both be enabled to 

 maintain the struggle for existence. This is what 

 actuall}'- occurred : the two organisms seem to have 

 made an agreement to assist each other. Whether 

 this was a truly altruistic motive, or whether it 

 was a case of necessity is rather difficult to deter- 

 mine. It was most likely a case of necessity ; that is, 

 the mutualistic association was compulsory in order 

 to prevent extinction. No matter which was the 

 prime motive, it remains a fact that the alga and 

 fungus finally entered into an association which was 

 mutually beneficial. This association is very different 

 from parasitism (antagonistic symbiosis), and is recog- 

 nized by scientists as a specialized form of mutualistic 

 symbiosis, designated as individualism ; the organisms 

 which enter into the formation of symbiotic associations 

 are known as symhionts. 



The relation of the symbionts under discussion 

 (fungus and alga) was, in a sense, complementary : one 

 supplied what the other lacked ; there was a harmoni- 

 ous and equable assignment of labor ; each did that for 

 which nature had best fitted it. In fact, we may draw 

 therefrom a wholesome lesson. It should teach us to 

 make that our life-work for which we are by nature 

 best fitted so as to accomplish a maximum of good 

 results. 



As to the division of labor in the establishment of 

 the lichen, the principal function of the fungus is to 

 supply protection ; that is, a mechanical function : the 

 chief work of the alga is to perform the function of 



