Additional Notes on Marine Pyrenomycetes. 191 
down into the cortex but fail to penetrate to any great depth. 
They all force their passage between the mucilaginous walls very 
much after the manner of a wedge. This forces the cells apart 
and they become crushed together into small groups as in Fig. 3, 4. 
Smaller branches then penetrate between these so that most of 
the cells become encircled by hyphae which appear to crush or 
strangle them and exhaust their contents by means of special 
bulging haustoria. Frequently the penetrating strands are several 
cells thick. The attack is confined mainly to the outer cortex, 
which becomes entirely disorganised ultimately, and, after the 
maturing of the fungus, breaks down leaving the underlying tissue 
freely exposed to the many saprophytes of the beach. 
Fig. 3. Hypodevma Laminaria. 7, stalk showing infected areas (a) ; 2, 
surface view of a enlarged ; 3, section of thallus with densely crowded 
perithecia ; 4, section of thallus enlarged showing developing perithecium (a), 
intermediate stage (b), mature form (c) and branching perithecium ( d ) ; 5, asci 
(a), paraphyses (b), ascospores (c). 
The perithecia are formed soon after infection, and rapidly 
develop over the entire blackened area. They are densely crowded 
together (Fig. 3, 3), and on surface view present the characteristic 
ostioles of the Hysteriineae, as depicted in Fig. 3, 2. They are 
parallel to the long axis of the host, and occasionally open by a 
