Proceedings 25 
in the diagram, the apex of the perithecium with its drop of 
mucilage usually comes into contact with a new substatum. 
This is frequently the leaves of various plants which grow 
underneath the trees on which the Phyd/actinia occurs— 
such as Violets, Plantain, Dogs’ Mercury, &c, Now under 
certain conditions, chiefly atmospheric—the mucilage sets 
hard, with the result that the perithecium becomes fixed 
upside down on the new substratum. So firm is this re- 
attachment that it requires, relatively, considerable force to 
remove the perithecium with a needle. 
It is only quite recently that this curious phenomenon 
of the turning over and refixing of the perithecium has 
become known. Previously it had been the cause of lead- 
ing systematists into error. In the first place the various 
plants (herbs growing under the trees on which the Phy/- 
lactinia occurs), on to the leaves of which the perithecia 
have fallen and have become refixed, have been and are 
still given as ¢rue host-plants of the Phyllactinia, whereas 
in reality Phyllactinia is absolutely confined to ¢rees. Fur- 
ther, when perithecia have fallen off they have frequently 
become re-attached to the «fper surface of leaves, either 
of their own tree or of plants underneath. This had led 
to the false description of the fungus as being sometimes 
epiphyllous, whereas it is always, when really growing, truly 
hypophyllous, t.e. confined to the lower surface of the leaf. 
Thirdly, the phenomenon has been the cause of the 
making of two supposed new species, and, moreover, won- 
derful species while they lasted! 
In 1882, a fungus was described under the name of Phy/- 
lactinia fungicola, and was stated to be parasitic, not, like 
the rest of the EZrysyphacee, on the leaves of flowering 
plants, but on another fungus, i.e. on the pileus of Boletus 
duriusculus, a fleshy fungus belonging to the Polyporee. 
This P. fungicola, however, proves to be founded simply 
on perithecia of P. cory/ea which, falling off from the leaves 
of a tree above, had become re-affixed to the pileus of the 
_ Boletus growing underneath. 
In 1899, curiously enough, a similar error was repeated. 
_ A fungus was described, as one of the Evysiphacee, under 
