Lecture XI — 151 — ■ Theories 



by Pfeffer." Kamienski (1884), finding Monotropa roots felted 

 with hyphae which prevented any direct contact of the plant with soil, 

 concluded that the fungus is its nutrient provider. "There is no other 

 way by which nutritive solutions may pass and provide the roots of 

 Monotropa, except the way of the mycelium." Fluid intake was also 

 posited by Issatschenko (1913) : "Disappearance of starch from 

 the nodule (of Trihulns) was observed which, according to Noel 

 Bernard, increases the osmosis of the cell and with it the water in- 

 take ; and in spite of Pavillard's recent criticism, the author con- 

 siders the relation between mycorrhizae and intake of water as un- 

 questionable." 



This was the idea which Frank originally adopted. As reported 

 by Klebs, the fungus, which is to be regarded as a parasite in its 

 colonisation and entrance, causes the host-tree no more damage than 

 that an organ is developed which supplants the regular roots of the 

 tree in taking in water and inorganic salts from the soil. As water 

 cultures indicate, the tree is not dependent for its existence upon the 

 fungus although it is evident that with fungal aid the tree grows all 

 the more thriftily. Yet the fungus seems in its development confined 

 to the tree, since efforts were not successful to grow the fungus on 

 culture media. Frank regarded his discovery of mycotrophy in 

 cupulifers as "ein neues Beispiel von Symbiose im Pflanzenreiche" 

 and stated (1885a) that "der Pilz als der alleinige Zufuhrer alles 

 fiir den Baum erforderlichen Wassers und Nahrmaterials aus dem 

 Boden erscheint." This statement is simply an amplification of 

 Pfeffer's earlier statement about Neottia. 



Miehe (1918) adopted the same idea when he said that myco- 

 trophy is a more or less developed modification of nutrient salt 

 acquisition. 



Mycophagy: — But as Frank continued to study mycorrhizae, 

 he saw digestion of the mycelium and was led to develop another 

 idea which may be termed "mycophagy". According to this concept, 

 the "fungus-eating plants" are able to draw their victim into the 

 protoplasm, there to tend it and make it large, and finally to digest 

 it, and thus the rich protein production of the fungus is made use of. 

 One of the two symbionts seems to have the advantage of the other 

 in that it appears as the raw material for the other. Stripped of its 

 fattening-pen implications, this concept has persisted. It was adopted 

 and modified by Magnus (1900) for Neottia: So far as purely 

 anatomical structures indicate, the physical significance of the 

 digestion-cells consists in an exclusive use for the higher plant by 

 which the substance-rich fungus is killed, digested and excreted ; the 



