ON THE MORPHOLOGY OF HEMILEIA VASTATRIX. 3 



Oil coffee from Sumatra.-^ Such are, shortlv, the external features 

 of the " disease spot," and we may now pass on to the details of 

 form and structure of the parasite itself. 



Since the main facts of development are now discovered, it 

 will be perhaps the simplest plan to trace the history of the 

 adult fungus from the JJredos'pore — to relate, in fact, what occurs 

 after sowing the spores on coffee, giving the details of structure 

 as we proceed. 



The Uredosjwre (" Sporange" of Abbaj and Morris) is figured 

 on Plate I, fig, 1 , in various positions, and is seen to be a 

 somewhat kidney-shaped body, broader, and rounded at the free 

 end, and slightly tapering at the other, where it is attached by a 

 very short pedicel to the spore-bearing structure hereafter de- 

 scribed (PL III, fig. -iO, c and/'). The free upper surface is convex 

 from before backwards and from side to side, and is studded 

 with small solid papilise. The remainder of the surface forms 

 two converging, slightly flattened sides, which gradually meet 

 below in a broad, rounded, saddle-like ridge. This is quite 

 smooth, concave from before backwards, and convex from side 

 to side. The vertical transverse section of such a body is some- 

 what triangular, with rounded corners ; but various figures are 

 obtained by projecting the several oblique optical sections as it 

 rolls over (PI. I, figs. 1 — 3). The upper side alone is normally 

 ornamented, though the papillae at times occur on the upper 

 portions of the otherwise smooth sides ; these papilise are out- 

 growths of the thick eorosjwre, and are usually pointed and 

 regularly distributed on its free surface (fig. 6 d). 



The granular protoplasmic contents of the spore are enclosed 

 by a delicate hyaline endospore, which becomes readily seen on 

 germination, or may be detected by such reagents as sodic- 

 chloride, sugar solution, &c. (figs. 6 and 7), which cause it to 

 contract away from the exospore, to the inner surface of which 

 it was before applied (fig. 4). The contents are usually coloured 

 orange red, and at times contain oil drops of an intense orange- 

 red tint (fig. 5) ; as a rule, however, the granular matrix is uni- 

 form throughout in the fresh spore. Under certain conditions the 

 orange tinge is lost, and the contents of the spore become grey 

 and cloudy. With these and other abnormal changes we are 

 not here concerned. The size of these Uredospores averages -^^-^ 

 inch long by -rrhis broad and deep. 



After lying in water for some hours it commonly happens 

 that many of these spores become filled with spherical vacuoles, 

 closely packed in the granular matrix, of equal or unequal size, 

 and varying in number accordingly. A common appearance is 

 that figured in fig. 7, and the impression of a sac filled with 

 1 Loc. cit., PI. 13, figs. 10, 11 and 12. 



