Orchid Mycorrhiza. J. Ramsbottom. 29 
and as in the larvae of certain aphids, coccids, etc., where yeasts 
occur as more or less definite structures, 
MYCORRHIZA. 
That the roots of many plants have the threads or mycelia of 
fungi associated with them has become very well known during 
the last eighty years. It is of interest to find that cells con- 
taining fungi were first figured in an orchid (though not very 
clearly) by Link* in 1840, who observed them in the young 
seedling (protocorm) of Goodyera procera. He did not hazard a 
guess as to their nature—his idea being that the cells were filled 
with colourless granular material which finally disappeared. 
At the beginning of the forties of last century the naturalists 
of this country who were curious in botany were very interested 
as to whether Monotropa Hypopitys was parasitic on the roots 
of beech in a manner similar to Lathraea. In 1842 we have 
T. G. Rylands} writing ‘‘On the nature of the byssoid substance 
found investing the roots of Monotropa Hypopitys.”’ Rylands 
concludes that “the ‘byssoid substance’ is really fungoid, and 
performs no essential function in the economy of the Mono- 
tropa.” It is, however, to Reissek} (1847) that we owe our first 
real knowledge. He examined numerous plants and came to the 
conclusion that fungi were normally present within the cortical 
cells of the roots of various flowering plants, being best de- 
veloped in the underground roots of orchids. In these he studied 
most of the native and several exotic genera. He found that in 
Orchis Morio, for example, the fungus was present in almost all 
the cortical cells, whereas in the tropical species the fungal 
masses were arranged singly at the periphery. The presence of 
fungi was most frequent in underground roots, less usual in 
superficial ones and very rare in aerial roots exposed to the 
light. Moreover Reissek attempted to extract the fungus from 
the roots. In those days of imperfect technique it is not so sur- 
prising that he failed as that he should have made the attempt. 
The fungus he obtained he named Fusisporium endorhizum: it is 
probably one of the common saprophytic species of Fusarium 
so abundant in soils. 
Another type of association between fungus and root is also 
well known, particularly in forest trees. Here the fungus 
mycelium forms a sort of mantle round the.root, in contrast to 
being within the cells of the cortex. Apparently Hartig first 
* H. F. Link, Icones selectae anatomico-botanicae, 11, p. 10, t. VII (1840). 
+ T. G. Rylands, On the nature of the byssoid substance found investing 
the roots of Monotropa Hypopitys. Phytologist, 1, pp. 341-8 (1842). 
+ S. Reissek, Uber Endophyten der Pflanzenzelle, eine gesetzmassige den 
Samenfaden oder beweglichen Spiralfasern analoge Erscheinung. Naturwiss. 
Abhandl. von W. Haidinger, I, pp. 31-46 (1847). 
