56 BIOLOGICAL LECTURES. 



pointed out by Sarauw in his review of the subject in 1893 

 (Rodsymbiose og Mykorrhizer, Copenhagen, 1893) comprise our 

 information upon this phase of the subject. 



All known species of mycorrhizal fungi may therefore be 

 included in the Oomycetes, Pyrenomycetes, Hymenomycetes, and 

 Gasteromycetes. The independent culture and identification 

 of these fungi offers a most alluring field to the mycologist, 

 and the exploitation of this work will doubtless result in the 

 setting up of scores of new species, the erection of genera, 

 the addition of new chapters to the life history of polymorphic 

 forms, and the furtherance of our knowledge of the morphology 

 of this great group of organisms, all of which will be of vital 

 importance in the determination of the essential features of 

 the general physiological value of mycorrhizas and the humus 

 relations of the higher forms. 



The widespread occurrence and distribution of mycorrhizas 

 render this adaptation of high importance in the nutrition of 

 the greater number of the perennial seed plants. At the pres- 

 ent time no reports are at hand of any attempt to use our 

 information on this subject in horticultural work, or in the cul- 

 tivation of economic forms, although I confidently predict that 

 it will ultimately be found of high value in the transplantation 

 and growth of woody plants, shrubs, and trees cultivated for 

 fruit, foliage, and other products ; a forecast easily compre- 

 hended when we glance at the vast agricultural importance of 

 the results of our study of the leguminous tubercles, which are 

 in fact a special form of mycorrhizas. 



Since the above lecture was written, Bernatsky's paper has 

 come to hand, in which he transfers the species of Nectria seen 

 by Wahrlich in Vanda tricolor to Hypomyces, and finds that H. 

 Vand<z (Wahrl.) Bernts. also unites with Vanilla aromatica and 

 P silo turn triquetrum to form mycorrhizas, and that Hypomyces 

 Psiloti Bernts. is the fungal symbiont in the mycorrhizas of Psi- 

 lotum. (J. Bernatsky. Adatok az endotroph mykorhizak ismere- 

 tehez. Termeszetrajzi Fuzetek. 22 ; 88. 1899.) 



