36 
Geo. K. Sutherland. 
These small spherical or pyriform fruiting-bodies contain a 
small number of asci which are of various ages and formed 
successively. The diversity in shape of mature asci, found even in 
the same perithecium, prevents their form being taken as a 
distinctive feature, notwithstanding the fact that it is often so used 
by the systematist. While many are broadly oblong and curved 
as in Fig. 1 ,4 a, others have long, tapering, much thickened apices 
almost completely pierced by narrow canals with slightly swollen 
lips as in Fig. 1 ,4 c. Frequently the thickened apical portion 
forms half of the total length of the ascus when mature. Paraphyses 
are wanting. 
The ascospores, eight in each ascus, are fusiform, hyaline, 
uniseptate and slightly constricted. Each cell becomes biguttulate 
when ready to be dispersed (Fig. 1 ,4 b). 
Not only is the mycelium of this fungus slimmer than that of 
Mycosphcerella ascophylli, first noted by Church in 1893, and 
described and named by Cotton in 1907; perithecia, asci, and 
ascospores also differ. These points alone are sufficient to justify 
its being regarded as a separate and distinct species. 
The ascospores are set free from the perithecia about the same 
time as the oospheres are being liberated. They become entangled 
in the mucilaginous inner persistent oogonial wall surrounding the 
latter. There they germinate and their germ-tubes gain entrance 
to the developing oospore either directly or sometimes a short 
mycelium is formed which penetrates slightly later. Thus the 
fungus finds its way into the intercellular spaces at a very early 
stage in the development of the young alga. Infection is rendered 
doubly sure by a vegetative process. Mixed with the paraphyses 
in the conceptacles are loosely coiled, much branched hyphae. 
These frequently become entangled in the mucilaginous coating 
enveloping the oospheres and are torn off as the latter are ejected. 
This mycelium is also capable of growing and gaining entrance to 
the developing oospore, when it again lodges between the young cells 
Curiously no perithecia have been observed in the thallus of 
Pelvetia canaliculata var. libera (Oliver) although abundant mycelium 
is present. This form, found only at Blakeney, reproduces by 
vegetative means alone. The fungus has adopted a similar habit 
being carried into the new shoots before they separate from the 
parent plant. The absence of perithecia, correlated with the absence 
of reproductive bodies in the algal host, shows how close the union 
between the two has become. 
