<E:cidwospores. 23 
spores of Chrysomyxa) the alternate cells remain sterile, 
so that instead of a long continuous series of spores, we 
encounter a series of perfect spores alternating, with 
variously shaped abortive cells, which may be shrivelled into 
fibres as in Restelia (Plate II. Fig. 9), or variously flattened as 
in Chrysomyxa (Plate II. Fig. 8). The further development 
of the spores consists in the cuticularization of their exterior. 
How this cuticle arises is not clear, whether from a meta- 
morphosis of the mother-cell, or from a separate develop- 
ment. The cuticle is in almost all species variously 
roughened by a number of minute points, spines, or very 
minute warty protuberances. By treatment with caustic 
potash these prominences disappear. According to De 
Bary’s* most recent views, he would appear to maintain 
that all zcidiospores are developed with alternate abortive 
cells. 
The pseudoperidium of the ezcidia is formed in the 
same manner as the spore-series, only the cells are sterile 
and empty, instead of being filled with coloured proto- 
plasm (endochrome). They are, however, developed in 
linear series, the larger and more mature being uppermost, 
the younger and smaller below; in fact, we may look upon 
the peridium as being developed from a circle of basidia 
surrounding the hymenium. The pseudoperidial cells are 
held pretty firmly together by an intercellular substance. 
They are variously altered by mutual pressure, being 
flattened, oval, oblong, square or rhomboidal, and always 
larger than the spores. The peridial cell-series are con- 
tinued upwards until they arch over the spores and meet 
those of the opposite side, so that they form a complete 
investment above and around the ecidium. As this body 
grows it comes nearer the surface, until at last it is covered 
by the epidermis alone, through which it may be seen 
* De Bary, ‘‘ Vergleichende Morphologie und Biologie der Pilze,” p. 76. 
