OLPIDIUM 89 



delicate mycelium, in the cortex of the root, 30-33 /x diam., 

 wall 10-12 /x thick. 



Protomyces pachydermus (Thum.) forms rather prominent 

 brown warts on leaves and leaf-stalks of carrot and dandelion. 



Resting-spores subglobose, wall pale brown, 14-24 /x 

 diam. 



Protomyces menianthis (De Bary) forms small clusters of 

 warts seated on red, then brown, patches, on leaves of Meni- 

 anthes trifoliata and Comorum palustre. 



Resting-spores subglobose or angular, brown, 20-40 /x 

 diam. 



Protomyces art (Cooke) forms irregular bleached patches 

 on leaves and leaf-stalks of Arum maculatum the warts are 

 not prominent. 



Resting-spores subglobose, brown, 14-20 /x diam. 



Protomyces purpureo-tingens (Mass.) forms elongated or 

 broadly effused patches of a red or purple colour on the 

 cotyledons and young leaves of the sunflower and garden 

 specimens of Smilacina. 



Resting-spores solitary, rarely two, subglobose, 25-28 /x 

 brown wall, minutely warted. 



Protomyces concomitant (Berk.). This pest was described 

 by Berkeley in Gard. Chron., 1882, p. 397, as destructive to 

 cultivated orchids, appearing on the leaves under the form 

 of somewhat pale, moist spots. 



Resting-spores globose, pale amber. 



I have no knowledge of this parasite, which so far as I 

 am aware has not been observed since its discovery by 

 Berkeley. 



OLPIDIUM (A. BRAUN) 



Vegetative condition passive naked protoplasm, the pro- 

 duct of one spore. This enters a cell of the host and 

 becomes surrounded by a wall, the contents of which 

 become resolved into i-ciliate zoospores, which escape 

 through a long beak reaching beyond the host-cell. In 

 other instances the cell becomes thick-walled and forms a 

 resting-spore, which in turn gives origin to zoospores. No 

 sexual reproduction. 



The total absence of mycelium and the presence of a 

 long beak to the cell, through which the zoospores escape, 

 are the chief features of that genus. 



