384 CHRYSOMYXA 
Gardens, Glasnevin, Dublin, on Oncidium varicosum and O. Forbesti. 
Others of the same character were also seen there by Sir Frederick Moore 
on Epidendrum vitellinum and Lycaste Skinneri. These tropical parasites 
are imported with the plants, and occasionally spread to a small extent, 
under glass, in this country. Persistent examination of such imports 
would no doubt discover still others of the same kind, 
Chrysomyxa Rhododendri De Bary. 
Aeidium abietinum A, et S. Consp. p. 120 p.p. 
Uredo Rhododendri DC. Flor. fr. vi. 86. 
Chrysomyxa Rhododendri De Bary, in Bot. Zeit. 1879, p. 809, pl. 10, 
f.1—6. Sacc. Syll. vii. 760. Fischer, Ured. Schweiz, p. 426. 
[&cidiospores. Aicidia irregular, membranaceous, com- 
pressed and elongated parallel to the mid-rib of the leaf (up 
to 3 mm. long), erumpent on transverse yellowed zones, at length 
irregularly torn, whitish; spores more or less ellipsoid, yellowish, 
1745 x 12—22 w; epispore thin, thickly verruculose except 
for a smooth longitudinal stripe.] 
Uredospores. Sori almost always hypophytlous, on yellowish 
or brownish spots, minute, roundish or oblong, scattered or in 
small groups, at length pulverulent, orange; spores in chains 
with intercalary cells, irregular or oval, verruculose, orange- 
yellow, 17—28 x 15—22 yw, without perceptible germ-pores. 
[Teleutospores. Sori similar, in densely clustered groups, 
brownish-red ; spores single or in the centre of the sorus several 
(46) superposed in a row, prismatic, 20—30 x 10—14yz; 
epispore colourless, thin, but with an annular thickening at the 
summit of the uppermost cell.] 
[Acidia on leaves of Picea eacelsa, August—October ;] 
uredospores on Rhododendron hirsutum, Douglas Castle, Lanark- 
shire, June, 1913 (D. A. Boyd). 
While this book was passing through the press, Mr D. A. Boyd kindly 
communicated specimens of this most interesting find. It occurred in 
small quantity, and only uredospores were observed. Description of the 
other forms after De Bary. This parasite is very common in Switzerland, 
in all parts where the Fir and the Alpine Roses occur together. The 
teleutospores germinate in June or July and the spermogones and ecidia 
appear on the Fir leaves from that time onwards, The xcidiospores can 
at once infect the Rhododendron leaves, where the mycelium winters, 
