170 Cintraciia. 



Anthistiria^ 

 26. Cintractia exserta McAlp. 



Sori ill spikelets, at first enveloped by a grayish membrane which gra- 

 dually decays, exposing the dark-brown to black mass of spores. 

 The elongated spore-mass, generally about | cm. long, consists of 

 several diseased and deformed spikelets blended together and a 

 central core of plant tissue running through. 



Spores olivaceous, smooth, globose to subglobose, or shortly 

 elliptical, sometimes slightly angular, 6-8 ^t diam. or 6-8 x 6-6*5 fji. 



On Anthistiria ciliata L. f. — Kangaroo grass. 



Victoria — Kiewa Valley, Nov., 1902 (Eobinson). Plenty Kanges,. 

 Nov., 1909 (C. French, jun.). 



In order to understand the appearance presented by this smut, it is ne- 

 cessary to know the structure of the normal inflorescence. The fertile spike- 

 lets bear a long, rigid, sinuous awn, over 6| cm. long, and this has generally 

 disappeared in diseased specimens so that they are readily recognised. The 

 ovaries are also shortly stalked, and since the development of the ovary is 

 prevented by the smut, it is the stalk which is distorted and destroyed by it. 

 Several undeveloped spikelets have become blended together, so that in longi- 

 tudinal section there are several such stalks seen. 



Pi Sfore formation.— In a cross-section of a diseased spikelet the relation 

 of the various parts is clearly seen. There is an outer colourless layer of tissue, 

 representing the enveloping membrane and consisting of an epidermis of 

 flattened cells and fungus filaments beneath. There is also a central core 

 of plant tissue, consisting of parenchymatous cells studded with fibro-vas- 

 cular bundles, and the whole is surrounded by a ring of fibro-vascular bundles. 

 The parenchymatous tissue and a portion of each bundle are stained blue by 

 Schulze's solution, showing the presence of starch. Between the central 

 core and the outer membrane there is a dense mass of spores, the formation 

 of which is clearly seen. Surrounding the ring of fibro-vascular bundles 

 is the colourless stroma from which proceed the spore-bearing filaments. The 

 spores are seen at first as minute colourless points, soon assuming a round or 

 oval shape. They are at first embedded in the gelatinous mass formed by 

 the deliquesced walls of the spore-bearing hyphae. Gradually they become 

 more or less rounded in shape, acquire an olivaceous tint, and with a firm 

 wall they become the mature spores. They are closely aggregated together 

 towards the outside and the development is clearly from the centre out- 

 wards, all the hyphae being spore-forming. 



Scattered among the spores here and there and sometimes forming chains 

 as in Plate XXXVIII., Fig. 100, there are colourless cells, generally resembling 

 those inside the epidermis forming the membrane, but they are as a rule 

 larger, thicker walled, and apparently undergoing rapid division. They 

 are stained yellow by Schulze's solution like the cells of the membrane. The 

 origin of these cells is apparent, and may be traced to the inner layer of the 

 membrane. The sterile fungus threads constituting the membrane tend to 

 break up towards the interior into their component cells or rows of cells. 

 The individual cells become globose or oblong with much-thickened walls, 

 which always remain hyaline, and these cells become detached and mixed up 

 with the spores. 



(Plates XVI., XXXVIII.) 



