24 



British Uredinece and Ustilazinece. 



shining as a small yellow tubercle. The epidermis becomes 

 ruptured by the pressure of the young growing aecidium from 

 below ; and, either before or soon afterwards, the pseudo- 

 peridium itself gives way at its summit, exposing the ripe 

 aecidiospores. The ruptured peridium now becomes re- 

 curved, and, as seen from above, the aecidium 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 ascidia. 

 The aecidium and 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 

 outwards, and they are car- 

 ried away by air currents, 

 rain, and by any cause that 



bition, 1884, for the Gardener's Ch7-onicle, clial'f^c ■f-ViP' 1-incf t-ilanf Tf 



September 6, 1884, p. 308. MiaKCb LUC nobt-piant. II 



the affected plant be grown 

 indoors or continually covered by a bell glass, so as to 

 prevent any injury to the aecidium itself or any agitation 

 of the host-plant, the aecidium elongates itself in a cylin- 

 drical manner. This was strikingly shown in a specimen 

 of ^c. 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- 



Fig. I. — ^-Ecniiuni berberidis. A, with 

 normal pseudoperidia ; B, with abnormally 

 elongated pseudoperidia. Figured by Mr. 

 Worthington G. Smith from an experimental 

 culture of the author's in the Biological 

 Laboratory of the International Health Exhi- 



