84 THE AMERICAN MONTHLY [March 



seedlings soon perish, whereas those provided with my- 

 corhiza will all thrive. Similarly by other experiments it 

 has been proved that it is from the leaf-mould that the 

 mycorhiza gains its food, and that mycorhiza is not 

 formed if the plants are grown in sand watered with the 

 substances used for the growth of the seedling. 



Here then we have exactly the reverse of what took 

 place in the case of the lichens. Here the advantage 

 would seem to be chiefly on the side of the green plant 

 and not on the side of the fungus, which can itself derive 

 all its nutriment from the surrounding soil, while the 

 green plant would not he able to get much nourishment 

 from this decaying vegetable mould. Indeed the seed- 

 lings of oaks and beeches when they germinate in their 

 natural conditions in the forest would all die if it were 

 not for the mycorhiza which, until their roots have pene- 

 trated the layers upon layers of dead leaves and have 

 reached the soil proper, supplies them with all the nour- 

 ishment they need. 



The yellow Bird's Nest orchis (Monotropa) grows 

 under exactly these conditions too, and its curious inter- 

 lacing root system, which has often the appearance of a 

 bird's nest, is also covered with a mycorhiza. This my- 

 corhiza nourishes it so efficiently that the Monotropa has 

 been able to dispense with its green leaves entirely, and 

 its stock is only covered with a number of yellow scales. 

 This of course points also to its long standing association 

 with a mycorhiza, for such an essential characteristic as 

 chlorophyll is not readily lost in the evolution of a plant- 

 It was the absence of the green color which had led 

 to the supposition that Monotropha was parasitic on the 

 roots of trees, whereas if parasitic at all, it is parasitic on 

 a fungus. But as it is the mycorhiza which seeks out the 

 Bird's Nest orchis, we must assume that the fungus too 

 derives some benefit from this association, though at pres- 



