152 Ustilago. 



Spores globose to subglobose or ellipsoid, olive-brown, densely 

 waited, 8-11 /( diam., or 10-12 x 7-8 /<, occasionally reaching 

 a length of 14 /■. 



On Agropijron scahnim Beauv. 



Victoria — ^Burnley, near Melbourne. Ardmona, Oct., 189-5 

 (Robinson). ^ Mvrniong, 1900, Dec, 1901. Nov., 1904 and 

 1906, and Feb.,' 1909.' Mt. Blackwood, Jan., 1903. Elmore, 

 Apr., 1906. Rainbow and Lake Albacutva, Oct., 1908. Dookie, 

 Dec, 190.3 and 1907. Ardmona, Oct., 1909 (McLennan). Plenty 

 Ranges, Nov., 1909 (C. French, jun.). Angustown, Dec, 1909^ 



Tasmania— Hobart, Feb., 1907 (Rodway). 

 South Australia — According to Cooke. 



The membrane enveloping the sori consists mainly of the epidermal 

 tissue of the plant. 



I am indebted to the Director of the Royal Gardens, Kew, for specimens 

 of this species collected by Colenso in New Zealand in 1849. 



In the Agricuhuml Gazette of New South Wales a new species was 

 described upon Agropyron scahrum as U. agropyri, but it was afterwards 

 discovered that the material contained a mixture of Danthonia and Agropyron, 

 and that it was really U. readeri Syd., which was there described as U. 

 agropyri McAlp. 



Spore formation. — A section of the ovary shows a central core of vascular 

 tissue, sometimes very much reduced, with irregular outline and projecting 

 processes. From the margin of this tissue the spores are developed, at first 

 as minute colourless points, and gradually become coloured and mature. 

 They radiate from the centre tow^ards the circumference, where they form a 

 continuous mass of olive-brown spores surrounded by the membrane. The 

 membrane is ruptured, and the loose powdery spores escape. 



Germination. — The spores germinate freely in water, and in about a 

 couple of hours there were indications of the germ-tube. Brefeld^ has 

 described the germination from a specimen on Agropyron orientale Roem. 

 and Schult. The spores germinated readily in water, but in a peculiar manner. 

 Several germ-tubes were apparently produced from the spore at the same 

 time, but all save one remained very short. This one elongated considerably 

 forming transverse septa behind as the contents moved towards the apex. 

 If the earliest stages of the germination are carefully observed, it will be seen 

 how this arises. The germ-tube is originally simple and unbranched, con- 

 sisting of three cells, of which only the lowest or rarely the two lowest grow 

 out directly into long filaments, without the formation of conidia. With 

 the outward growth of the lower cell the apex is turned to one side, so that 

 at an early stage it gives the impression of three germ-tubes originating at 

 the same time. If instead of water a nutritive solution is used, then it is 

 quite different. A normal promycelium is formed, producing conidia, of 

 which there was not even a trace in water. The single promycelium consisted 

 of three cells, but when several were produced from the same spore, each was 

 reduced to two cells. The elongated ellipsoid conidia sprouted even Avhile 

 still attached, but more luxuriantly when detached. The sprouting conidia 

 were very slow in their growth, and inclined to form filaments before the 

 nutritive solution was exhausted. In none of the cultures did fusions or 

 aerial conidia occur. 



(Plate XXIX.) 



