Uredospores. 29 
branches is destined to produce a uredospore. At first 
they are of uniform diameter, but soon the upper end 
dilates so as to become club-shaped (Plate III. Figs. 2, 
5). Into this dilated extremity the protoplasmic contents 
of the hyphez are gradually emptied; and thus by their 
continued accumulation it becomes almost spherical. This 
dilated tube-end is now full of granular protoplasm, towards 
the centre of which appear a few orange granules (in the 
orange-spored species), while externally it becomes in- 
vested with a thin cell-wall of its own (Plate III. Fig. 3). 
The cell increases in size, its walls in thickness, and its 
contents become more and more distinctly coloured. The 
orange granules, which consist of reddish-yellow, oleaginous 
particles, are at first confined to the centre of the cell, 
and gradually increase in number from the centre out- 
wards; so that we frequently observe immature spores, 
which are orange only in their centre, having the centre 
surrounded by a hyaline zone. The spore has at this 
stage ‘of its development two coats—the outer, which is 
extremely thin and is the dilated mycelial hypha; and the 
inner, the proper wall of the spore. The latter increases 
somewhat in thickness, although it always constitutes a 
comparatively thin investment. These two coatings 
become closely applied to one another. The exospore, 
which is at first smooth, becomes, in most species at their 
maturity, variously roughened by the appearance of minute 
projections from its surface (Plate III. Fig. 4). These may 
be in the form of short, fine spines, when the spore is said 
to be finely echinulate, or the prominences may be shorter 
and less acutely pointed (verrucose). De Bary has shown 
that the spores of many of the Uredinez owe their rough- 
ness to minute, densely crowded, prismatic, staff-like pro- 
cesses, between which similar smaller processes are closely 
packed. The irregularities of the exospore disappear under 
