NOTE. 
PRELIMINARY NOTE ON GASTRODIA ELATA AND ITS MYCO- 
RHIZA. — A peculiar habit of Gastrodia data and its highly reduced vegetative organ 
led me to undertake the present work. After careful observations in the field, 
cultivation-experiments, and cytological study, I have arrived at results, the chief 
points of which may be stated as follows : — 
The vegetative organ of Gastrodia data is represented simply by a tuberous 
rhizome. It forms mycorhiza with the mycelium strand of Ar miliaria mellea , 
generally called Rhizornorpha subterranea . The cytological features tend to show 
the mycorhiza to be an endotrophic form. However, the direct connexion of the 
endophyte with the Rhizornorpha strands vigorously vegetating in the surrounding 
medium indicates the physiological relationship between the two symbionts to be 
similar to that in a typical ectotrophic mycorhiza. 
The infection by the fungus is effected by a sucker-like branch of the Rhizo - 
morpha strand, which penetrates into the cortical cell layers of the tuber, partly 
compressing the underlying cells and partly dissolving their walls. This process 
is essentially the same as that presented by the haustorium of Cuscata. The infecting 
strand sends out separate hyphae which spread intracellularly in a definite zone 
under a few layers of subcortical cells. The extension of the endophyte is limited 
within a certain area around the infected spot. 
The mycorhizal cell-layers may be distinguished into three regions, according 
to the structure of the cells and the nature of the hyphae which compose them. The 
first region consists of the outer two or three layers, which contain a densely entangled 
mass of comparatively thick-walled hyphae. A similar convolution of hyphae is 
observed in the next one or two layers composing the second region. In this region 
the hyphae are generally thin-walled and of various breadths, and are often arranged 
in pseudo-parenchymatous form. The innermost layer constitutes the third region ; 
these cells are the largest and contain each a few, slender, less curved hyphae. 
The different hyphae of the endophyte have essentially the same structure as 
those composing the Rhizo7norpha strand; the hyphae of the first, second, and third 
regions correspond respectively to the outer interwoven hyphal branches usually 
forming the gelatinous investment, the inner cortical hyphae, and the slender hyphae 
composing the secondary pith of the strand. The hyphae of each region show 
characteristic alterations. They are permanent in the first region, as may be seen in 
the so-called fungus host-cells, and undergo self-disorganization in the second, 
leaving their walls as irregular masses, while in the third region they are mostly con- 
sumed by the host-cells. 
[Annals of Botany, Vol. XXV. No. XCVIII. April, 1911.] 
