104 MR. Н. М. WARD ON THE STRUCTURE, DEVELOPMENT, 
cavity of the perithecium ; when mature, the spores, and sometimes paraphyses, are seen 
escaping through a round aperture at the apex. 
The paraphyses, which are produced in immense numbers between the asci (fig. 68, a & b), 
are extremely slender straight filaments, with one or two hardy discernible septa, and a 
few granules scattered in the interior of their cells (fig. 68, с). 
The ascus is a delicate, transparent, clavate sac, containing granular protoplasm, nearly 
the whole of which becomes converted into eight oblong spores, each at first resembling 
a stylospore, but eventually becoming relatively shorter and stouter. 
When ripe the ascus (fig. 68, d) absorbs water, and bursts in the following manner :— 
The outer, extremely delicate and transparent wall, becomes divided along a line passing 
round the ascus a little below the apex; and a portion is thus separated like a cap from 
the rest. The gelatinous material lining this outer wall, and filling up the spaces between 
the spores (epiplasma of De Bary)—the remains of the original protoplasm which was not 
used up in forming the spores, and which absorbs the water and produces the pressure and 
tension resulting in rupture—then becomes extruded as a glairy mass, in which the 
spores are embedded. Curious axial rows of granules which appear during this process, 
as if connecting the spores end to end, are very characteristic, and seem to indicate 
the protoplasm remaining between the diffluent masses lining the ascus. 
The ripe spore is a broadly oblong body, with a slight median constriction, corre- 
sponding to a faintly marked septum near the equatorial plane. About four large oily- 
looking globules occupy the interior; and it frequently happens that the septum cannot 
be distinguished until these are made to disappear by alcohol or ether. 
On germination, each of the two cells of the spore produces a terminal hypha (fig. 67), 
which extends for some distance without branching, eventually becoming brown, how- 
ever, and forming the typical mycelium already described. 
PHYSIOLOGICAL AND PATHOLOGICAL. 
It is now time to consider the question, what obvious effects, if any, are produced by 
the presence of this organism on the leaves of the phanerogam ? In this connexion, also, 
my researches apply more especially to the specimens on Michelia, though some points 
of importance are to be mentioned as regards Citrus. 
It has been already stated that at a very early stage the naked or almost д cell from 
which the Algal thallus originates (the zoospore which has come to rest, in fact) becomes 
closely applied to the cuticle of the leaf, and, indeed, practically becomes fused as it were 
into its substance. This phenomenon appears to be of an order similar to the boring 
process commonly found in the germination of the zoospores of certain parasitic Fungi, 
e. g. Phytophthora*, and can probably be imagined only as due to a power on the part of 
the zoospore to dissolve the material of the cell-walls «с. at that point. In the case of the 
present Cryptogam, however, this does not proceed so far as to produce a perforation into 
‚ the leaf of Michelia ; the zoospore merely fixes itself solidly into the cuticle, and proceeds 
to divide. However, from the character of the attachment of the rhizoids and larger disk 
of the thallus, it appears certain that these also have the power of partly fusing into the 
+ De Bary, * Développement des quelques Champignons parasites,” Ann. d. Sc. Nat. sér. iv. Bot. tom. хх. бю. 
