306 



MYCORRHIZAE AND MYCOTROPHY 



Alonotropa will grow independently of tree roots and that the 

 roots of both the tree and the Alonotropa are invested with a 

 similar fungus mantle. Furthermore this mantle is organically 

 connected with hvphae that course between the cells of the root 

 cortex. In criticism of Kamiensky's work, however, it may be 

 indicated that he did not present experimental evidence that either 

 the trees or the Alonotropa are dependent upon the fungus. 



mill 



^pvjni 



Fig. 48. Diagram of young root, the upper side mvcorrhizal, the lower 

 normal. The root-hair zone, K (in black), occurs near the root tip, M. 

 The increased absorbing surface in A, B, C, and D (in black) is to be 

 compared with that in E, F, G, and H. The surface area active in ab- 

 sorption in mvcorrhizal roots must also take account of the surface area 

 of the fungus filaments. (After Hatch.) 



From about 1840 the association of truffles, especially with oak, 

 beech, and hornbeam, attracted botanical attention. Certain early 

 students of this problem definitely established that the mycelia 

 of truffles are connected with the roots of these trees, but the 

 relationship was supposed to be parasitic. At first Frank's interest 

 in the matter was centered upon the possibility of cultivating 

 truffles and other hvpogeous fungi, especially Elaphomyces {rranu- 

 latus, in the forest. As an outgrowth of this interest he established 

 the fact that the roots of certain trees, especially members of the 

 Cupulifereae, are invariably invaded by fungi. Aloreover, he was 

 led to formulate the theory that the relationship is not one of para- 

 sitism but of definite beneficial symbiosis, in which the fungal 



