262 Weiss . — Mycorhiza from the Lower Coal-Measures. 
devoid of contents, but a few of the larger more rounded ones show homo- 
geneous contents. In one or two instances vesicles were found among 
the cells containing the dark clumps and these contained what appear 
to be spores (Plate XIX, Fig. 6), but as they are really in the medio-cortex 
it is possible that they were formed in a different manner from the vesicles 
described above. In some cells lying near those with large vesicles (see 
Plate XIX, Fig. 5) there are found curious granules distributed very evenly 
through the cell and apparently attached to the cell-wall. The nature and 
formation of these I was not able to elucidate from the specimens at my 
disposal. 
In the medio-cortex, as described above, we find the characteristic 
clump formation (see Plate XVIII, Figs. 1, 3, and Plate XIX, Fig. 4) — 
the clumps consisting no doubt partly of the cell-contents, partly of 
fungal filaments ; but they are as a rule so dark in colour that no details 
of their structure can be made out. They are connected to the cell-walls 
by threads, which are sometimes very delicate and appear as if they were 
protoplasmic filaments, though they are probably contracted hyphae, as 
these can in some cases be seen very clearly as shown in Plate XIX, Fig. 4. 
These hyphae are, however, usually thinner and more delicate than those in 
the outer layers of the cortex. In this particular the fossil mycorhiza 
agrees with recent ones in which various observers have noted this difference. 
The fossil mycorhiza can of course give us no clue as to the formation 
and significance of these clumps, but their excellent preservation in a 
fossil condition may be considered to support the view of Werner Magnus 
(’00), that they consist of the non-digestible and unalterable remains of the 
Fungus after the host-plant has derived from it all possible nutriment. 
For the fact that these clumps are so well preserved would indicate that 
the Fungus had passed into an unalterable condition before fossilization. 
Should the same degenerative changes have taken place in the medio- 
cortex of the fossil plant as take place in recent mycorhizae these would 
readily explain such appearances of degeneration as one meets with in some 
of the specimens. Thus in Fig. 8 will be seen curious vacuolated masses 
which, as indicated by the presence of delicate radiating filaments, are 
probably produced in a similar way to the mycelial clumps. They 
obviously correspond to the so-called ‘ traubenformige Korper ’ described 
by Bernatzky (’ 99 ) in the rhizome of P silo turn. Ultimately they would 
seem to break up into separate particles not unlike bacteroids (Fig. 7), but 
which may also be compared to the curious ‘ Eiweisshyphen ’ described by 
Magnus (’ 00 ) in some of the cells of the medio-cortex (Verdauungszellen) 
in which the host-plant is digesting the Fungus. 
The obvious resemblance between these clumps in the fossil plant and 
those of recent mycorhizae, together with the close agreement in the 
structure and behaviour of the Fungus in the outer layers of the cortex, 
