342 Groom . — On Thismia Aseroe ( Beccari ) 
from the nucleus unless it be leaving the cell altogether. 
Eventually, however, distinct localized enlargements form on 
the hyphae, which thus assume bloated irregular moniliform 
shapes. The hyphae branch but feebly in these cells. The 
hyphae usually pass on to younger cells of the same layer, 
i.e. the hyphae tend to run longitudinally, but occasionally 
they send branches into the cells lying within, namely, the 
limiting layer. The mycelia live much longer than those of 
the mediocortex, and in old parts they may be found with 
deeply staining protoplasmic contents. When they do die, 
which rs earlier than is the case with the mycelia in the 
sheath, there is little or no deposit of excreta, and all that 
remains of them is a shrunken clump of thin hyphal walls. 
The Mycelia in the Limiting Layer (Figs. 15, 16). 
The mycelia in the limiting layer in every way form a 
transitional stage between those of the exocortex and those 
of the mediocortex. The hyphae curve sharply, swell 
irregularly into one or two bladders which are formed only 
in contact with the nucleus of the host-cell ; the unswollen 
portions retain their embryonic slender calibre. The bladders 
are not so regularly spherical as those of the mediocortex, 
but often the primitive egg-like form characteristic of their 
early state in the mediocortex persists. Furthermore these 
bladders preserve their protoplasmic contents much longer 
than do those of the deeper cortical layers ; and often in old 
parts these densely protoplasmic bladders at first sight look 
like large single spores. 
Previous Records of Formation of Lntercalary Bladders on 
Hyphae of Mycorhiza. 
The first record of intercalary hypertrophies of mycorhizal 
hyphae is that of Mollberg 1 J who found them in Platanthera 
bifolia and Epipactis latifolia . He wrote : ‘ Es waren inter- 
calare und auch terminale knopfformige, aber auch lange 
1 Mollberg. Quoted in Wahrlich’s paper. 
