THE FUNGUS-ROOT (MYCORRHIZA). 179 
tissue. This attachment of fungus to root does not kill the 
tree, we are not sure that it does any harm, it may indeed be of 
considerable use to it. The immediate effect upon the root is 
an arrest of the growth in length with more frequent branching, 
that is, the formation of a fungus-root. The actual inception and 
development of a fungus-root is not easy to follow. This close 
association of the two organisms is generally regarded as a form 
of symbiosis. 
Eighty-two years ago Link observed fungi in the seedling 
protocorm of an orchid, Goodyera procera, but he did not realise 
that the substance was fungoid. It was not until seven years 
afterwards, in 1847, that Reissik recognised fungi in the roots 
of orchids and other plants. 
I do not propose to give a_ historical resumé of the progress 
of knowledge respecting the fungus-root, as the literature of the 
subject up to so recent a date as 1922 is cited in an article, 
entitled “ Orchid Mycorrhiza,’! by J. Ramsbottom. Although 
this article treats particularly of orchid fungus-root the references 
are not restricted entirely to papers concerning these plants. 
It will be, however, convenient to note the three Periods in the 
study of the fungus-root as recognised by Gallaud.2 They 
are :— 
First PERIOD 1840-1885. Very little detailed work was 
described at this early stage. Writers recorded the fact that 
fungi were in several instances found closely related to the 
roots of various plants. 
SECOND PERIOD 1885-1894. It was during the first year 
of this period that A. B. Frank’ made known the results of his 
researches on the fungus-root. He introduced the term mycorr- 
hiza to describe it, and he further differentiated two forms of 
mycorrhiza. In one the fungus threads penetrate below the 
epidermal tissues and enter the cells of the root to which they 
attach themselves, in the other, the hyphae form a mantle around 
the root. The first form he designated as endotropic mycor- 
rhiza, the latter as ectotropic mycorrhiza. These two forms 
are not distinctly separate, for it is now known that in the second 
I. Ramsbottom, J., ‘‘ Orchid Mycorrhiza.” Brit. Myc. Soc., vol. viii., pp. 28-60, 1922. 
z. Gallaud, F., ‘‘ Etudes sur les mycorrhizes endotropes.” Rev. Gén. Bot., Xvii., pp. 5 et 
passim, 1905. 
3. Frank, A. B., ‘‘ Ueber die auf Wurzelsymbiose beruhende Ernahrung gewisser Baume 
durch unterirdische Pilze.” Ber. d. deutsch. bot. Gesell, pp. 128-145, 1885. 
