66 Transactions British Mycological Society. 
lings and endophyte, the production of ‘‘synthetic”’ seedlings 
is not a simple operation. The age of the seedling, the suit- 
ability or otherwise of the rooting medium, the age of the 
fungus culture and the nutrient on which the endophyte is 
cultivated outside the plant are all critical factors, as are also 
doubtless such formal external conditions as temperature, 
moisture, and light. 
REFERENCES. 
(1) CuristopH, H. Untersuchungen iiber die mykotrophen Verhdltnisse der 
“Ericales’”’ und die Keimung von Pirolaceen. Beih. Bot. Centralbl. 
XXXVIII, pp. oy 157 (1921). 
(2) RAYNER, M. C. Obligate symbiosis in Calluna vulgaris. Ann. Bot. 
XXIX, Pp. 97-133 (1915). 
(3) TERNETz, C. ber die Assim, des atmosphar. Stickstoffes durch Pilze. 
Jahrb. f. wiss. Bot. (Pringsheim), xLiv, pp. 353-408 (1907). 
AN EOCENE MICROTHYRIACEOUS 
FUNGUS FROM MULL, SCOTLAND. 
With Plate VIII. 
By W. N. Edwards, B.A., Department of 
Geology, British Museum. 
Well-preserved fossil fungi are of comparatively rare occur- 
rence, and most of those so far described are found in petrified 
material. Names have certainly frequently been given to spots 
and markings on leaf impressions, which, however, rarely show 
any structure and are of very little botanical value. It is there- 
fore of interest to be able to record the discovery in some 
Tertiary Rocks of Scotland of an unusually well-preserved 
epiphyllous fungus. 
The Eocene interbasaltic beds of Mull contain a varied flora 
of ferns, conifers and dicotyledons mostly preserved as im- 
pressions. In a very few cases the actual leaf cuticles have 
remained practically unchanged in what has been called a 
“mummified condition,’ and by treatment with Schultze’s 
mixture or some other reagent can be cleared and examined 
microscopically. This method of preservation is familiar to 
palaeobotanists, who have found the details of stomatal structure 
and cell outline valuable aids to classification, especially in the 
case of certain gymnosperms. 
The microscopic fungus about to be described was found in 
the course of examining some linear coniferous leaves scattered 
on the surface of two slabs of rock in the Starkie Gardner | 
Collection (Specimens V, 14846 and 7). With the object of 
