SYMBIOSIS OF PHANEROGAMS AND FUNGI. 251 



off and used for the purpose is put into pure sand, is explicable in the same way. 

 Limes, roses, ivy, and pinks, the roots of which possess no mycelial mantle, are 

 notoriously propagated very easily by putting branches cut from them into damp 

 sand. Rootlets are at once produced on those parts of the branches which are 

 buried in the sand, and their absorption-cells carry on the task of taking up 

 nutriment from the ground. But though cuttings of oak, rhododendron, winter- 

 green, bog- whortleberry, and broom strike root, no progress in their development is 

 to be observed, because the superficial cells of the rootlets, in these cases, have not 

 the power of absorbing food when they are not associated with a mycelium. It is 

 only when the slips from these plants are put into sand with a rich admixture of 

 humus, the latter having just been taken from a wood or heath and containing the 

 germs of mycelia, that some few are successfully brought to further development. 

 The result is even then often not assured, and the cuttings of several of the plants 

 enumerated die even in sand mixed with humus before they have produced 

 rootlets. 



Seeing also that the result of attempts to rear seedlings of the beech and the fir 

 in so-called nutrient solutions, where there could be no question of any union with 

 a mycelium, has been that the plantlets dragged on a miserable vegetative existence 

 for a short time and ultimately died, we have good grounds for assuming that the 

 envelope of mycelial filaments is indispensable for the Phanerogams in question, and 

 that the prosperity of both is only assured when they are in social alliance. 



The facts ascertained in cases of analogous relationship lead one to expect that 

 the fungus-mycelia also derive some advantage from the flowering-plants, the roots 

 of which they clothe, and to which they render the service of acting as absorption- 

 cells. The benefit in question is undoubtedly the same as that derived by the 

 hyphse of a lichen-thallus from the enwoven green cells. The mycelial mantles 

 withdraw from the roots of the Phanerogams the organic compounds which have 

 been elaborated by the green leaves in the sunshine above-ground, and which are 

 conducted thence to all growing parts, that is to say, downwards as well as in other 

 directions, to the tips of the swelling and elongating roots. According to this, 

 therefore, the division of labour between the members of the alliance for joint 

 nutrition consists in the mycelium supplying the green-leaved plant with materials 

 from the ground, and the green-leaved plant supplying the mycelium with 

 substances which have been worked up above-ground in the sunlight. 



The range of species which live in a social union such as is here described is 

 certainly very large. All Pyrolacese, Vaccinese, and Arbutese, most, if not all, 

 Ericaceae, Rhododendrons, Daphnoidese, and species of Empetrum, Epacris, and 

 Genista, a great number of Conifers, and apparently all the Cupuliferae as well as 

 several Willows and Poplars are dependent for nutrition on the assistance of 

 mycelia. We find, too, that this condition recurs in every zone and in every region. 

 The roots of the Arbutus on the shores of the Mediterranean are equipped with 

 a mycelial mantle in precisely the same manner as those of the low -growing 

 Whortleberry of the High Alps. 



