24 British Uredinee and Ustilaginee. 
shining as a small yellow tubercle. The epidermis becomes 
ruptured by the pressure of the young growing zcidium from 
below ; and, either before or soon afterwards, the pseudo- 
peridium itself gives way at its summit, exposing the ripe 
zcidiospores. The ruptured peridium now becomes re- 
curved, and, as seen from above, the zcidium is cup-shaped, 
The white peridium contrasts with the golden yellow of 
the spores very strikingly. The peridial cell-series still 
show their linear origin by separating into teeth, the attach- 
ment being stronger from above downwards than laterally, 
This recurved, toothed mar- 
gin of the peridium is highly 
characteristic of the zcidia, 
Thezcidiumand its peridium 
consist at this stage of a few 
fully developed spores and 
cells above, and of a vast 
number of undeveloped 
spores below. As these latter 
mature they push the old 
ripe spores upwards and 
Fig. 1.—Ecidium berberidis. A, with OUtwards, and they are car- 
normal pseudoperidia; B, with abnormally 
elongated pseudoperidia. Figured by Mr. fied away by air currents, 
Worthington G. Smith from an experimental 
ee ae a 
September 6, 1884, p. 308. , ‘ “plant. If 
the affected plant be grown 
indoors or continually covered by a bell glass, so as to 
prevent any injury to the zcidium itself or any agitation 
of the host-plant, the acidium elongates itself in a cylin- 
drical manner. This was strikingly shown in a specimen 
of 4c. berberidis which I cultivated and exhibited at the 
Biological Laboratory of the International Health Exhi- 
bition, 1884, in which the peridia developed themselves 
into long curved cylindrical bodies. The above illustra- 
