124 
Transaction of the Royal Society of South Africa. 
Meliola jjeltata Doidge occurs on P. Thimbergii and P. falcata ; these 
two species have a very similar leaf structure, while that of P. elongata 
differs considerably, being quite of the ordinary mesophytic type. 
The leaves of the first two species have a thick cuticle, especially on the 
upper side, and just under the epidermis there are one, two or three rows of 
sclerenchyma fibres. These form a continuous band on the upper surface, 
but on the lower surface they are interrupted in the neighbourhood of the 
stomata. 
The fungus examined was on the lower surface of P. Thunhergii ; it 
closely follows the contour of the leaf, completely blocking the depression 
above the stomata and pressing on to the guard-cells. This circumstance, 
which has not been mentioned before, was noticed in a number of the species 
examined and is apparently of constant occurrence (Fig. 4). 
Pig. 4. — Hyphae of M. peltata on leaf of Podocarpus Thunhergii (low magnifi- 
cation, comp. oc. No. 1), showing five haustoria, and the hyphae following 
the contour of the leaf into the depression above the stoma, and completely 
blocking the stoma. 
No haustoria were seen penetrating the guard-cells, but numerous thick- 
walled filaments penetrate the thick cuticle, traverse the epidermal cells, and 
the sclerenchyma fibres if these are encountered (Fig. 5), and enter the first 
layer of chlorophyll-containing mesophyll cells. The latter are considerably 
disorganised and stain deeply with the methyl blue. 
Where it begins to penetrate the cuticle the haustorium is slightly 
bulbous or funnel-shaped, and measures 4*6-5 /x in diameter (Fig. G). This 
diameter immediately below^ decreases to about 1'5 /x, often continuing to 
taper slightly till it reaches the mesophyll cell, where it expands into a 
globular or ovoid vesicle, 4"5-5 fx diam. The penetrating filament is brown 
throughout, but becomes paler as it grows away from the external hypha ; 
the vesicle is delicate, hyaline, stains a clear blue, and has a single, central. 
