Lisl of Mycclozoa, Shn'a\shitry, (iiilich}ui Lislcr. 17 



//. Vesparium (Hatsch) Macbr. B. 



Arcyria cine re a Pers. T., H. 



A. pomifoniiis (f.eers) Rost. I\, II. 



A. denudata ([..) Sheldon. P., H., T., B. 



A. incarnala Pers. P., H., jB., T. 



A. nutans (Bull.) Grev. P., H. 



PRESIDENTIAL ADDRESS. 



By Annie Lorrain Smith, F.L.S. 

 THE RELATION OF FUNGI TO OTHER ORGANISMS. 



The subject I have taken for consideration has recently 

 been impressed on my mind in my stud}' of the develop- 

 ment of lichens and of the relationship and inter-action 

 between the fungus and the alga, the two constituents of the 

 lichen thallus. 



From the mass of material bearing on the question I 

 have selected some of the more important facts and instances, 

 the results of research carried out by workers on many 

 different aspects of this subject. It is impossible to do 

 much more than give a sketch, as the subject is a very vast 

 one. 



Fungi, as we know, are dependent on other organisms 

 for the carbohydrates, without which life cannot be sus- 

 tained. -To obtain these at second hand, as it were, is their 

 great task in life, and it has been achieved in various ways : 

 fungi have demonstrated that there are many different 

 methods of securing the means of subsistence. 



The only sources from which organized products can be 

 obtained are either from dead material of plants or animals, in 

 which case the relation is harmless or saprophytic, or from 

 living bodies, by a parasitism which is antagonistic and 

 harmful. There is however a third possible relationship 

 known as symbiosis or mutualism, in which the two 

 organisms — tlie body yielding the carbohydrates and the 

 fungus — are mutually helpful. One might also include the 

 symbiosis of bacteria with the animal organism, which is 



