2 74 British Uredinece and UstilaginecE. 



yellowish-brown, subtransparent, smooth or obscurely punctate 

 or granular, 5-8/x in diameter. 



Synonyms. 



Reticularia segetum. Bull., " Champ.," vol. i. p. 90, t. 472, 

 fig. 2. With., vol. iv. p. 356. Purton, vols, ii., iii. No. 1079. 

 Johnst., " Flor. Berw.," vol. ii. p. 203. Grev., " Flor. Edin.," 

 p. 442. 



Uredo segetum. Pers., " Disp. Meth.," p. 56. Berk., " Eng. 

 Flor.," vol. V. p. 314. 



Ustilago carbo, Tul. Cooke, " Hdbk.," p. 512. 



UstUago segetum (Bull). Winter, loc. 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, saiiva, Tf'iticum vulgare, Hordeum vulgare, 

 distichum, hexactichum . 

 May and June. 



Biology. — See p. 74, and p. loi. Mr. J. L. Jensen, of Copen- 

 hagen, has recently published his observations on the biology of this 

 species. He has succeeded 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. tecta and tntda. Of these 

 nuda is by far the most common. The spores have a tinge of yellow 

 when seen eti masse ; they are rather smaller than those of tecta. 

 The affected ears are completely destroyed, excepting the rachis, and 

 the spores soon scattered. Tecta, on the other hand, has somewhat 

 larger spores, which, when seen e7t 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. Tecta has been 

 found in the island of lona, but it doubtless occurs all over Britain. 



