350 U. MARSHALL WARD. 



twigs of the mycelium, others remain short and stumpy, as 

 did the earliest ones, and from these, as before, haustoria 

 descend into the epidermal cells of the host-plant (fig. 6). 

 In this manner the network of mycelium becomes closely 

 anchored, at pretty regular intervals, to the epidermis. 



But, besides tracing these haustoria by examination en 

 face, they, and their origin and course, may be rendered 

 more evident in vertical sections of the leaf, especially when 

 hardened and stained. Specimens are well shown in fig. 8, 

 where the razor has passed nearly through the points of junc- 

 tion between haustorium and hypha. But, although the haus- 

 toria are especially produced by the stumpy branches, they 

 are not confined to these, but may arise along the course 

 of the thicker or thinner main branches, as shown in 

 fig. 6. 



Moreover, some of the stumpy side-branches do not pro- 

 duce haustoria at all, but become broken up into short 

 more or less quadrate bodies, by splitting at the closely-set 

 septa. These fragments of the mycelium appear to repro- 

 duce the fungus in a vegetative manner, by simply putting 

 forth hyphse from any point (fig. 7). By the above-described 

 means, then, a more or less symmetrical, radiating mycelium 

 is produced on the surface of the jasmine leaf, gathering 

 strength as it grows and as new haustoria branches, and 

 anastomoses become established, and presenting the appear- 

 ance to the unaided eye of a delicate, dark coloured, cloudy 

 spot. 



When thus developed, the appearance of reproductive 

 organs soon becomes evident. The rudiments of these arise 

 as follows. 



Here and there, at certain points in the network, one of 

 the short stumpy lateral branches is noticed to form nume- 

 rous lateral lobes, which remain closely appressed side by 

 side, and gradually build up a flat, disc-like expansion (figs. 

 9 to 13). The successive lobes, which collectively form this 

 disc, become cut oft" by closely-set septa as they become 

 completed, and the formation of the whole strongly reminds 

 one of the dichotomous mode of growth of some Algse {e.g. 

 the thallus of Coleochsete). This is still evident in an 

 advanced disc, as fig. 13, which was very carefully drawn 

 with special reference to the position of septa, &c. It will 

 be understood that the radial walls in such a disc result 

 from the coalescence of the out-growing lobes side by side ; 

 the tangential walls, on the contrary, are true septa. 



While this disc is commencing to form, or in some cases 

 (figs. 28 — 30) before the division and growth of the lobes 



