SYMBIOSIS OF PHANEROGAMS AND FUNGI. 253 



i membranous and transparent scales, and the extremity of each is bent back like 



a hook. The cylindrical flowers are developed at the top of the stem with their 



open ends turned to the ground, and are half-covered by the scales. Everything 



i about this plant (stem, leaf-scales, and flowers) is of a pale waxen-yellow colour, 



and the general impression it produces is much more that of a Toothwort, or one of 



the colourless forest orchids, than of a species of primula or winter-green. Towards 



autumn, when ripe fruits have been produced from the flowers, the hitherto 



drooping extremity of the stem lifts itself into an upright position, whilst the 



entire aerial portion of the plant turns brown and dries up. Every disturbance 



caused by the wind, however slight, shakes out of the spherical fruits many 



thousands of tiny seeds as fine as dust, which, like the winter-green seeds, consist of 



I only a few cells, and do not admit of the recognition of any diflerentiated embryo 



j within them. Moreover, underground, the rhizomes, from which the small group of 



] pale stems have arisen in summer, continue to live through the winter, and a 



j number of new buds are developed on them. On digging down to the hibernating 



i plant and removing the mould which conceals it, one finds at a depth of from 10 to 



40 centimeters bodies like coral-stems consisting of dense masses of roots crowded 



together and ramifying multifariously. All the root-branches are short, thick, 



fleshy, and brittle, and are matted together to form turf -like masses, which are not 



infrequently interwoven with the rootlets of pines, firs, and beeches, and have all 



their interstices filled with humus. Each rootlet is enveloped, right up to the 



growing apex, in a thick mycelial mantle. The hyphal filaments of this mycelium 



do not penetrate into the tissue of the root of Monotropa, nor do they send any 



haustoria into the superficial cells of these roots. The hyphae and the epidermal 



cells of the root are, however, in such close and continuous contact that sections 



exhibit a complete continuity of the tissues. 



Monotropa is therefore only able to withdraw nutriment from the hyphal weft 

 of the mycelium so far as its subterranean parts are concerned, and, seeing that it 

 is quite destitute of chlorophyll, and its aerial stem and leaves display no trace of 

 stomata, the possibility of creating organic matter and of adding in general to its 

 substance by means of its aerial parts is excluded. It therefore receives all the 

 materials of which it is constructed from the mycelium of the fungus, whilst it is 

 not in a position to render anything in return to this mycelium that it has not 

 previously derived from the latter. If the mycelium subsequently withdraws any 

 materials whatever from the still living or decaying Monotropa, the process is only 

 one of restitution and not of exchange. Thus, in this case, there can be no talk of 

 reciprocity in the processes of nutrition or division of labour such as occurs when 

 there is symbiosis. The Monotropa grows in height and in circumference entirely 

 at the expense of the mycelium in which it is imbedded, so that we have here the 

 remarkable phenomenon of a Phanerogam parasitic in the mycelium of a Fungus. 

 We so often come across the converse process in our experience that we cannot 

 easily familiarize ourselves with the idea of a flowering-plant draining the 

 mycelium of a fungus of nutriment: nevertheless there is scarcely any other inter- 



