88 West. — On Stigeosporium Marattiacearum and 
Whilst the above-described changes have been taking place in the spore 
wall, the cytoplasm, which at first consisted of dense granular protoplasm 
completely filling the interior of the spore, gradually decreases in bulk until 
in the ripe spore a condition is arrived at where the cytoplasm (proteid) 
occupies only a fraction of the interior of the spore, the remaining space 
being filled with oil (cf. Text-figs. 7, ii, and 8, ii, with Text-figs. 7, vii, 
and 8, ix). 
Thus, it would appear that the innermost wall is deposited at the 
expense of part of the original spore contents, whilst the greater part of the 
remainder of these cell contents is converted into oil. The innermost wall 
rapidly increases in thickness until in the mature spore an average thickness 
of 2-5 n is attained (Text-figs. 7, vii, and 8,ix). 
/3. Structure of the mature resting spores . 
The ripe resting spores possess three distinct walls, namely — 
1. An extremely thin smooth outer wall. This wall is colourless and 
is closely applied to the middle wall, from which it is indistinguishable 
in unstained preparations, but can readily be identified in stained prepara- 
tions of crushed spores. 
2. A thick (6 fx) middle wall. This wall consists of a transparent 
straw-coloured matrix which is traversed by a large number of canals 
or pores (average diameter o-8 f), which radiate from the interior of the spore 
(Text-figs. 7, vii, and 8, ix ; PI. Ill, Fig. 1, c,d,e,f,g). Each canal is not 
of uniform diameter throughout its length, but tapers towards the periphery 
of the spore (Text-figs. 7, ii-viii, and 8, iv-ix). 
The chemical nature of this substance could not be determined with 
certainty. It is very resistant to every reagent to the action of which the 
ripe spores were subjected. These included KOH, chlor-zinc iodide, eau-de- 
Javelle, concentrated HC 1 , &c., &c., but Kleinenberg’s haematoxylin stained 
it with difficulty (cf. Dastur ( 19 ), pp. 207-8). 
Irregular bands and markings of a deeper yellow colour ramify through 
this matrix and are clearly visible both in surface view and in sections of the 
spores (Text-figs. 7, ii-vii, and 8, iv-ix; PI. Ill, Figs. 1, a-g, 2, and 5B). 
The substance of which these bands are composed is equally resistant to the 
above-mentioned reagents, and all attempts to stain it failed. 
3. A moderately thick (2-5 f) inner wall. This wall develops very late, 
is generally not closely applied to the middle wall, and presents many of the 
reactions of cellulose. It is exceedingly tough, and even when the thick 
middle wall of the spore is crushed artificially this inner wall remains 
unbroken. 
On reaching maturity the spores become detached from their sup- 
porting hyphae, and are then found lying free within or between the cells of 
the host-root, which are sometimes forced apart by the growth of the spores, 
as is shown in Text-fig. 8, i. 
