New Marine Fungi on Pel vet 5a. 
35 
thin and membranous except at exposed tip. Asci cylindrical and 
curved, or tapering, thickened apex almost pierced by narrow canal, 
45-55/a x 15-20/a. Ascospores biseriate or bunched, fusiform, 
19-25/a x 4’5-5-5/a, hyaline, uniseptate, with slight constriction, 
cells biguttulate when mature. 
Hab. Symbiotic with Pelvetin. 
The very slender septate mycelium of this fungus permeates 
every portion of the thallus from holdfast to receptacle, running 
along the surface of the algal cells, with whose outer walls it is in 
very close contact. In colour it resembles the latter, and this, 
added to the extreme tenuity of the hyphae, may explain why it has 
been constantly overlooked. The threads, so fine as rarely to exceed 
1-1‘25/a in diameter, are difficult to detect without the aid of stains; 
iodine and fuchsin make them readily visible. 
The mycelium is entirely intercellular, never breaking through 
the soft slimy walls unless the cells have been attacked and partially 
broken down by parasitic fungi or bacteria beforehand. When the 
material is in this condition the course of the symbiotic mycelium 
cannot be traced with the same certainty. In the healthy thallus 
there is no such difficulty. The large intercellular spaces of the 
medullary tissue and cortex, kept moist continually by the swollen 
mucilaginous walls, form an ideal home for the hyphas whose branch 
tips penetrate even between the cells of the rind or limiting layer. 
The hyphse branch freely and are extremely numerous, forming a 
loose net-like web surrounding the cells. Altogether there is an 
immense length of fungus to unit-volume of the tissue, but with it 
all not the slightest trace of injury to the host has been noted in 
the hundreds of sections examined. 
The fungus grows along with the thallus and thus penetrates 
into the young receptacles, where it commences to fruit just as the 
reproductive bodies are being formed in the conceptacles. Minute 
perithecia are produced immediately under the rind, through which 
the tips burst and barely protrude when mature as in Fig. 1, 2 and 3. 
While the immersed portion of the perithecial wall remains thin 
and membranous, the small projecting tip becomes carbonaceous, 
and thus readily visible against the olive-green receptacles, so that 
at this stage the latter become marked by numerous small black 
specks as in Fig. 1, 1 (a). The perithecia are practically confined 
to the receptacles ; a few scattered ones may appear on the thallus 
immediately below, but they rarely, if ever, occur on the main 
vegetative body of the host. 
