54 Transactions British Mycological Society. 
been along a line similar to the Calluna type leading to infection 
of the embryo as apart from the seed-coat, and consequent 
continuous infection, it is more likely that in the typically non- 
mycorrhizal grasses such a union has been brought about by 
a subjection of a seed parasite. 
RELATION BETWEEN FUNGUS AND FLOWERING PLANT. 
Throughout the preceding pages incidental remarks have been 
made regarding the relation between the two constituents of the 
mycorrhizal association. The subject is one of extraordinary 
interest and of extreme difficulty. It does not seem possible to 
regard all such associations as being of the same nature or.as 
having arisen in the same way. 
As we have seen, Rylands was the first to record fungi in 
association with roots, though his account is not very clear: his 
idea that the fungus performs no essential function in the 
economy of Monotropa is one that has had few supporters. 
Reissek, who in many ways seemed before his time in his 
attitude towards the subject, regarded the regularity and per- 
manence of the presence of fungi in orchid roots as of great 
importance. He apparently considered that they were not 
absolutely necessary for the life of the plant and suggested that 
the orchid could generate without the root fungus in the same 
way that the greater number of flowering plants are able to 
propagate without flowers. 
The gradual realization of the dual nature of lichens brought 
in its train the conception of symbiosis, but the increasing know- 
ledge as to the nature of fungus-roots played a not inconsiderable 
part in the growth of the idea. 
From the year 1862 Tulasne began to consider the relation 
between the False Truffle (Elaphomyces) and the roots of trees 
as one not of simple parasitism as he had previously (1841) 
thought, but one by which both organisms benefited in some 
way. Pfeffer in 1877 took up this idea of mutual benefit and 
made it more precise. Other workers—Treub, Goebel, Kamienski 
—also regarded the relation between fungus and root as of this 
description. It is to the work of Frank, beginning in 1885, that 
we owe a proper conception of the widespread phenomenon and 
a clearly outlined theory of symbiosis between fungus and root. 
Naturally as more facts both of observation and experiment 
were obtained Frank’s original theory was somewhat modified 
—originally it was that plants with ectotrophic mycorrhiza did 
not themselves draw nutriment from the soil, but that the 
mycelial filaments which completely envelop the absorbent roots 
procure for it all its nutriment. Such roots always lack absorbent 
root hairs. The absence of these organs of absorption corre- 
