274 British Uredinee and Ustilaginee. 
yellowish-brown, subtransparent, smooth or obscurely punctate 
or granular, 5-8» in diameter. 
Synonyms. 
Reticularia segetum. Bull, ‘“‘Champ.,” vol. i. p. go, t. 472, , 
fig. 2, With., vol. iv. p. 356. Purton, vols. iL, iii, No. 1079. 
Johnst., ‘Flor. Berw.,” vol. ii. p. 203. Grev., “ Flor. Edin.,” 
Pp. 442. 
Uredo segetum. Pers., ‘‘ Disp. Meth.,” p. 56. Berk., “ Eng. 
Flor.,” vol. v. p. 314. 
Ostilago carbo, Tul. Cooke, “ Hdbk.,” p. 512. 
Ustilago segetum (Bull). Winter, oc. cit, p. 90. Cooke, 
“Micro. Fungi,” 4th edit., p. 229, t. v. figs. 98, 99. 
Exsiccati, 
Cooke, i. 54; ii. 428, 430, 432. - Baxter, 43. Vize, “ Fungi 
Brit.,” 31. 
On Avena elatior, sativa, Triticum vulgare, Hordeum vulgare, 
distichum, hexactichum. 
May and June. 
BIoLoGy.—See p. 74, and p. tor. Mr. J. L. Jensen, of Copen- 
hagen, has recently published his observations on the biology of this 
species. He has succeedéd in infecting oats, barley, and wheat, by 
removing the external envelopes of the seeds and applying the spores 
to the bare kernels. He finds that the varieties of U. segetum which 
occur upon the above plants are biologically distinct, the Ustilago 
from the one cereal being incapable of infecting the others. Upon 
barley he finds two well-marked forms, var. ¢ecfa and muda. Of these 
nuda is by far the most common. The spores have a tinge of yellow 
when seen e” masse; they are rather smaller than those of ¢ecta. 
The affected ears are completely destroyed, excepting the rachis, and 
the spores soon scattered. TZecta, on the other hand, -hgs somewhat 
larger spores, which, when seen e7 masse, are jet-black. ~The affected 
ears are nearly twice as broad as the healthy ones, and do not emerge 
from the top of the leaf-sheath, but burst through laterally. Each of 
the affected kernels retains its shape for a considerable time, being 
enclosed in a membranous investment. The spores escape through 
minute fissures which appear in this membrane. TZecta has been 
found in the island of Iona, but it doubtless occurs all over Britain. 
