38 
Geo. K. Sutherland. 
The disease is marked externally by the blackened circular patches 
shown in Pig. 2, 7, 2. Usually the margins of these become white 
owing to the disintegration of, and consequent chemical changes in, 
the rind of the host. The hyaline, slender, septate mycelium is 
entirely local, and is easily distinguished from that of Mycosphcerella, 
with which it is intermingled, by its greater thickness and irregularity 
as well as by its habit. Its average diameter is 2-2-5/x but frequently 
it reaches as much as 5/x at points where the branching is extensive. 
The spaces between cells become packed with the hyphae which 
penetrate the mucilaginous walls and become closely coiled round 
the living contents into which haustoria are sent as in Fig. 2, 4. 
At other times the tips of branches penetrate directly and act as 
absorptive organs. In this respect this plant differs markedly from 
the symbiotic fungus already described. 
Fig. 2. Stigmatea pelvetice. 1, thalius with diseased spots (a) ; 2, diseased 
patch enlarged ; 3, section showing perithecium (6) and pycnidium (c) ; 4, 
mycelium with haustoria ; 5, asci and paraphyses; 6, ascospore (a), pycnidio- 
spores (b). 
Growth is rapid and shortly after infection fruiting bodies 
appear on the blackened patches in the form of small pycnidia 
corresponding to the genus Phyllosticta. At first these are immersed 
but they become superficial by the disintegration of the surrounding 
tissue. The walls are thick and carbonaceous. Minute elliptical 
conidia are ejected from the small ostiole. The rapid infection, 
