NUTRICISM. 93 



have been named mycorhiza ^ or fungus-roots. Where, however, 

 new structures (swellings, etc.) are produced on the roots, as a 

 result of symbiosis with fungi or bacteria, the name mycodomatia 

 or fungus-chambers has been applied. 



One division of mycorhiza consists of those which live in 

 humus, and act as intermediaries in supplying their hosts with 

 nutritive material. In this case the fungus covers the host- 

 root like an outer covering, forces itself between the cells of 

 the outer layers, and produces haustorial branches in the interior 

 of the host-cells. These Frank designates as ectotrophic 

 mycorhiza. The remaining mycorhiza do not form such an 

 external sheath, but live inside the fungus-traps, and produce 

 tangled coils of hyphae in the root-cells of the host. These 

 Frank distinguishes as endotrophic mycorhiza. 



Ectotrophic Mycorhiza. 



(1) On non-chlorophyllous plants living on humus. 



Kaminski ^ was the first to observe that Monotropa hypopitys, a 

 non-chlorophyllous plant living rooted in forest-mould, possessed a 

 compact root system devoid of root-hairs, but covered with the 

 hyphae of a fungus. At the same time, he expressed the belief 

 that a symbiotic relationship existed between the fungus and 

 the roots of Monotropa, whereby the former supplied nutriment to 

 the latter. The fungus clothes the growing point, and extends 

 backwards to that part of the root which has ceased to elongate; 

 there the mycelium penetrates^ inwards between the root-cells, 

 and remains intercellular. The mycorhiza of Monotropa thus 

 showed complete agreement with those known earlier on the 

 roots of Cupuliferae,* and since proved by Frank to have a very 

 general distribution. Johow ^ has pointed out that an external 

 mantle of fungi also exists round the root-apices of Hypopitys 

 hypopliaegea, a holosaprophytic plant devoid of chlorophyll. 



' Sarauw, Rodsymbiose og Mycorrhizer saerlirj hos Skovtraeme, 1893. With 

 Bibliography. 



'^ Kaminski, M4m. de la soc. des sciences natur. de Cherbourg, T. 24, 1882. 



'Frank, Berichte d. deulsch hotan. Ges., 1885. 



''Miiller, Sludier over Skovjord som Bidrag til Skovdrykningeiis Theori, 187S. 



^' Johow, "Die chlorophyllfrelenHumuspflanzen," Pringsheim's Jahrbucli, 1889. 



