58 ECOLOGICAL RELATIONS OF THE FLORA. 



propulsion as in the Asconiycetes and Basidiomycetes, as has been 

 shown by Buller (1909), or biotic as in the Phalloids, etc., whose spores 

 are carried by insects. Fungi also show successions, as, for example, 

 the successive appearance of different species on fallen logs at chfferent 

 stages of decay and the zonation shown about a dung heap. 



The ecological relations depend on the life habit. If parasitic, the 

 problem is similar to the problem of the higher parasites, namely: 

 entrance of host, appropriation of the food supply, and reproduction. 

 The problems of immunity and virulence also come here. If sapro- 

 phytic, the problem is comparable to the problems of the green plants, 

 for saprophytic species are affected by climatic and by edaphic 

 factors, chiefly water and nutrient content. The former allows the 

 fungi to be classed as xerophytic, mesophytic or hydrophytic, while 

 the nutrient content probably accounts for the facts of successions 

 and the occurrence on distinct species of fallen trees, etc., or on distinct 

 kinds of soil, as Astraeus on sand and Hygrophorus miniatus in the bogs. 

 Climatic factors would be operative through the effect of light and 

 temperature, the former probably being more important. The fact 

 that fungi present spring, summer and fall aspects would probably 

 come from the effect of climatic factors. 



These things may be seen working in the general fungus layers but 

 as a group the fungi are much more important as biotic factors, pro- 

 ducing diseases and epidemics, and in the important activities of de- 

 structive metabolism and nitrification. 



Fungi have been listed from special forest associations (La Garde 

 1909) and a number of ecologists have listed the species along with the 

 higher plants. (Weber 1902) (Jennings 1909) (Ganong 1897).* The 

 group now requires a great amount of physiological work and nutrient 

 relation determination, and the forms present difficulties in the field 

 through their evanescence, size and periodicity (Harshberger 1904, p. 

 149) and from the fact that the presence of the mycelium is not always 

 betrayed by the production of a pileus, but notwithstanding these 

 difficulties they present attackable problems of distribution and ecology 

 which are worthy of notice. (For criticism of this view see Pound 

 and Clements, 1900, pp. 121-4.) 



PHYTOGEOGRAPHICAL RELATIONS. 



Sand Point is located in the Transition Zone, as outlined by Merriam 

 (1898), and its flora, disregarding species of continental distribution, 

 is about evenly divided between the so-called Boreal and Austral species. 



*Klebahn (1904, pp. 97-103) has attempted to connect the occurrence of certain heteroec- 

 ious forms of rusts with the formation in which the hosts occur, but the meagerness of observa- 

 tion of both host and fungi in the same formation makes his work largely conjecture. For 

 such analyses there is need for suitable lists. 



