1915] 



WESTERDIJK PHYTOPATHOLOGY IN THE TROPICS 



313 



Different groups of fungi are much less restricted in their 



geographical distributions than are phanerogams. 



Up to 



the present time, no special tropical families among the fungi 

 are known, and, as far as I know, the only fungus group 

 that has no representatives in the tropics is that of the Ery- 

 siphaceae. The secondary part which fungi play in the plant 

 diseases of the tropics is not caused by the absence of fungi, 

 but by the particular conditions which influence both the host 

 and the parasite, and their relations to each other. To estab- 

 lish the exact nature of these influences is a problem for the 

 future. 



