26 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Mycorrhizae, commensal root fungi, of pines and many other groups 

 might be of especial interest, first because the data they furnish might 

 be compared with those from rusts and other fungi, and, second, 

 because they produce lesions which possibly might be recognizable in 

 fossils. 



Fig. 3. — The Indian Ocean and the adjacent land areas. The dotted lines indi- 

 cate 2000 fathoms depth. (Modified from a map by W. & A. K. Johnston.) 



The fungi in general should be scrutinized for groups fitted for 

 such studies. Fungus diseases of plants are being more and more 

 studied and new data are thus being offered. 



Plants and their parasites, when studied by the von Ihering method, 

 will surely give very important results, but such study must be accom- 

 panied by further and laborious study of the structure, life history 

 and taxonomy of the .parasites. 



Fossil records of the hosts are of especial interest in biogeographical 

 problems and if these can be joined with fossil records of the parasites 



