77 1 
A sariim europaeum and its Mycorhiza. 
The appearance presented suggests that the fungus, on entering this layer 
of cells, has encountered some substance which has caused its death and 
disorganization, and probably partial digestion by the plant, the irregularly 
shaped mass left in the cells being composed of portions of fungus, which 
the plant is incapable of absorbing. Cells of this nature are to be seen in 
Figs. 2 and 3. Starch grains, when present in these or other cells of the 
plant, stain blue with iodine solution, and not red, as was the case in 
Thismia. 
The cells of the two or three layers external to that described above 
are for the most part filled with the coiled hyphae of the fungus, as is shown 
in Figs. 2 and 3. The fungal hyphae mostly run in a longitudinal direction, 
as illustrated in Fig. 2, and coil round and round the cell, which finally 
becomes filled with fungus ; the hyphae may infect the neighbouring cell by 
penetration of the cell-wall (see Fig. 6). Intercellular hyphae also occasion- 
ally occur ; these run a straight course between the cells and send branches 
into them which give rise to the coils mentioned above. 
The hyphae are very irregular in shape. Sometimes they are swollen 
out into bladder-like forms, as is shown in Fig. 4 ; at other times they 
resemble ordinary fungal hyphae. The bladder- like swellings occasionally 
found on them bear no relation to the cell nucleus, which when visible in 
mycorhizal cells is of normal size and appearance ; on the other hand, the 
nuclei of cells in portions of roots which are free from the mycorhizal fungus 
have sometimes been observed to be considerably enlarged and of abnormal 
shape. 
The fungal hyphae, which are densely filled with granular protoplasm, 
are non-septate and contain numerous small nuclei, which stain well with 
Benda’s iron-haematoxylin. 
The hyphae, unlike those of the fungus in Thismia , do not make 
straight for the cell nucleus, but, as stated above, form coils in the cells. 
The fungus is confined entirely to these few cortical layers in the vicinity 
of the stele, and shows no inclination to spread into the outer region of the 
cortex with its cells rich in reserve starch. Portions of fungal hyphae are 
shown in Figs. 4, 5, and 6. 
On some hyphae may be seen intercalary or terminal swellings of 
a spherical or a pear shape. These swellings, which are thick-walled, 
contain dense granular protoplasm and are multinucleate. They doubtless, 
if belonging, as I believe they do, to the mycorhizal fungus, represent its 
resting or reproductive stage. They are not very commonly met with, and 
it is just possible that they belong to a parasitical fungus which has also 
obtained an entrance into the root. When met with, however, they are 
invariably found in the inner cortical layers with the mycorhiza, although 
the hyphae bearing them are somewhat different in appearance, owing to 
their staining at times rather more deeply than those of the undoubted 
3 E 3 
