Kelley — viii — Mycotrophy 



Forest tree mycorrhizae receive continued attention from two of 

 the principal investigators of mycotrophy. Rayner (1941) has 

 summarized her own and related researches on the effect of composts 

 on tree growth. Melin's (1946) attention has been turned especially 

 to growth and anti-bacterial substances with respect to mycotrophy. 

 Recently fallen leaf-litter was found to contain water-soluble sub- 

 stances that promoted the growth of litter-decomposing and mycorrhi- 

 zal fungi. Cognate studies have been made by Harley but his latest 

 paper was not available at this writing. 



Synthesis of Boletus with pine seedlings to form synthetic 

 mycorrhizae was performed by Ferreira (1941), thus confirming 

 the discoveries of a number of earlier investigators. What is said 

 to be the first synthesis of alder nodules was accomplished by Plotho 

 (1944). 



Obligate symbiosis is still questioned, but it is claimed by Bose 

 (1947) for Casnarina under the name of hereditary symbiosis. 

 Mycelium extended into every organ of the tree, spreading from the 

 seed-coats. 



Among herbaceous plants, orchid mycotrophy claims the attention 

 of Burgeff (1943), and Sprau (1939). The Burmannias and their 

 mycotrophy were investigated by Ciferri ; and at his laboratory at 

 Pavia there is active interest in our subject. To the several papers 

 on mycotrophy in halophytes was added one by Fries (1944) : nine 

 out of ten halophytes examined were mycotrophic. Again, in game- 

 tophytes of the fern Botrichium, Naryana (1939) described endo- 

 phytic infection. So, too, in hepatics described by Peyronel (1942) 

 from Italy: double infestations occur and the symbiosis is much 

 affected by edaphic conditions, but in general the relation seems to 

 be of mutual benefit. A noteworthy contribution to the study of 

 herbaceous mycotrophs was made by Barrett (1947), who suc- 

 ceedeed in isolating Rhizophagus in pure culture. 



There is a continually increasing emphasis on the physiology of 

 mycotrophy, and several contributions to this subject have been 

 made recently. From a yellow Corticiiim a pigment called "corticro- 

 cin" was isolated (Erdtman, 1947), "the first n-polyneoid diacid 

 found in Nature." Another paper reverted to the Stahlian concept 

 of stomata in relation to mycotrophy. It will be recalled that Stahl 

 believed mycotrophs had a reduced number of stomata and a limited 

 transpiration stream, mycotrophy supplying the nutrients otherwise 

 supplied by photosynthesis. A recent investigation (Linsbauer & 

 Ziegenspeck, n.d.) concludes that amongst mycotrophs there is a 

 significant reduction in number and formation of stomata. Extreme 

 mycotrophs resemble holoparasites. A third physiological paper 



