Weiss. — A Mycorhiza from the Lower Coal-Measures. 261 
cell-contents in ' Neottia , Psilotum and other plants according to Werner 
Magnus (’00) and Shibata (’02). But as these are very delicate, and soon 
disappear, we should not expect to find them in the exo-cortex of the 
fossil plant. Otherwise the latter presents very much the same appearance 
as it does in recent plants. In one or two cases the numerous hyphae 
attached to the inner walls of these cortical cells remind one of the 
mycelial pegs described by Groom (’95) in the roots of Galeola. 
For the most part the hyphae seem to be intra-cellular, but there are 
indications that a few of them run between the cells. In no case, how- 
ever, is there any sign that the Fungus was in any way destroying the 
tissues of the host-plant. In some of the cells of the exo- cortex curious 
pear-shaped bodies are found at the ends, or apparently at the ends, 
of certain hyphae. These may be fairly numerous, as in Plate XIX, 
Fig. 3 , or there may be only two or three in a cell. They are generally 
most numerous in the sub-epidermal cells, while in the deeper layers of 
the exo-cortex they are fewer in number, larger in size, and more rounded. 
They resemble somewhat the pear-shaped swellings described and figured 
by Williamson (’81) on the hyphae of Peronosporites antiquarius , a Fungus 
found in the bark of Lepidodendron. Such pear-shaped bodies are, however, 
of very common occurrence in the outer cortical layers of recent myco- 
rhizae. Thus in Psilotum , Janse (’97) figures a dozen of them in a sub- 
epidermal cell, just as they occur in the fossil mycorhiza. The nature 
of these vesicles, formed by endophytic Fungi, is a much-disputed point. 
Some authors look upon them as possibly of the nature of reproductive 
organs. Thus Bruchmann (’85) considered that they might possibly be 
oosporangia, while Goebel (’87) thought they might be gonidia (Dauer- 
gonidien) in the case of the Fungus inhabiting Lycopodium, , which they 
supposed to be related to Pythium. Groom (’95), on the other hand, who 
made a very careful examination of these bladders and their mode of 
formation in the mycorhiza of Thismia , found that they were not terminal 
but intercalary dilatations, though appearing terminal by hypertrophy. 
He is consequently inclined to attribute a nutritive function to them, 
and regards them as of importance in increasing the absorptive area of 
the Fungus which is supposed to feed upon the host-plant in the outer cor- 
tical layers. This view of the purely vegetative character of the vesicles had 
also been entertained by Mollberg, who was apparently the first observer of 
these intercalary hypertrophies of the Fungus (in Platanthera and Epipactis ). 
Groom found that the vesicles accumulated a large amount of densely- 
staining cytoplasm, which afterwards became vacuolated and diminished 
in amount, ultimately degenerating and depositing ‘ a homogeneous yellow 
substance in which are rod-like bodies which remind one of the regular 
rod-like bacteroids in leguminous tubercles.’ 
In the fossil plant the vesicles, whether large or small, are generally 
