i6o Usiilago. 



Then in 1892 Massee determined a specimen sent from Victoria bv Reader 

 on Danfhonia penicillnM as TJstUaqo destruens Schieclit., and the same species 

 had been previously recorded on Danthonia by Coolie^. Finally, in 1896*, I 

 described what was really the present species under the name of U. agrofyri, 

 as there was a mixture of material of Agropyron and Danthonia which 

 was afterwards separated out. 



It simply remains now to compare this species Avith that of TJ . destruens 

 Schlecht. = U. pamci-miliacei (Pers.) Wint. = Sprosporiiini 'panici-miliacei 

 (Pars.) Takahashi. 



As Takahashi^ has clearly shown the species referred to by Massee is a 

 Sorosporium and not an Ustilago, the spore-balls being rather evanescent at 

 maturity. The smut pustules are covered by the epidermis of the host with 

 a layer of sterile hyphae in close contact and fibro -vascular bundles traverse 

 the pustule together with hyphal strands. 



The external appearance as well as sections of U. readeri clearly show how 

 distinct this species is. On the stem it forms elongated bJister-like swellings, 

 and the leaden-coloured epidermis soon raptures to allow the escape of the 

 spores. It sometimes completely surrounds the stem which is longitudinally 

 furrowed as the swollen epidermis bursts and exposes the spores. 



A cross-section of the stem shows the hollow cavity in the centre, and in 

 the plant tissue immediately beneath the epidermis scattered patches of 

 spores are developed. Sometimes these isolated patches blend here and there 

 and form a larger one, and finally the epidermis is elevated and ruptured to 

 allow of the escape of the spores. 



A cross-section of the axis of inflorescence shows the central core of plant 

 tissue either solid or with a small cavity, and surrounding that the patches of 

 spores are developed, so numerous and so close together, that they ultimately 

 form a dense continuous mass, covered by the epidermis until it is ruptured. 



A cross-section of the ovary shows the central vascular bundles comple- 

 tely surrounded by dense masses of spores. The spore-forming hyphae 

 have evidently penetrated the larger vessels as they are seen to be filled with 

 spores at different stages of development, and finally the entire tissue of the 

 ovary would be replaced by spores. 



Germination. — The spores germinated readily in water and also very 

 luxuriantly in Cohn's modified solution. Fresh spores and spores one year 

 old readily germinate, but when the material is two years old only an occa- 

 sional spore germinates. It is one of the easiest sjDores to germinate, and if 

 not too old can always be relied upon to do so in a few hours. Spores taken 

 from Danthonia psniciUata F. v. M., collected in December, 1905, germinated 

 in July, 1906, and also in December of the same year. The germinating 

 spores figured (PL LIII., Figs. 203, 204, 205) are from Danthonia penicillata 

 collected in December, 1908, and they were germinated at once. 



The spores when germinated in water put forth in a few hours 

 a straight promycelium which at first is non-septate (PL LIII., Fig. 203). 

 Then it elongates and becomes divided by several septa, when 

 it may either produce conidia (PL LIII., Fig. 204) or elongate further 

 (PL LIII., Fig. 205). The conidia are produced laterally and termin- 

 ally, only a few lateral and one apical. They are colourless, cylin- 

 drical, rounded at the ends, 6-9 /.t long, and may or may not be attached by 

 a short sterigma. Only occasionally one produces another by budding while 

 still attached. The promycelium, however, may and often does forego the 

 formation of conidia. It grows out at the apex of the septate portion or 



