South African Perisjjoriaceae. 
125 
deeply staining nucleus. The shortest penetrating filaments, found where 
the chlorophyll-containing cells were immediately under the epidermis, were 
17-20 /X long; the average length where two sclerenchyma fibres were 
traversed was 40 /x (Fig. 6), and in exceptional cases where there were three 
layers of fibres under the epidermis they were up to 60 /x long. Cases were 
observed where the haustorium pierced through the lateral wall of the 
epidermal cell (Fig. 7). 
The haustoria could be readily picked out with the low power of the 
microscope ; fairly thick sections were better than extremely thin ones, as 
the latter did not show the entire course of the penetrating filament. The 
filaments were for the most part straight and perpendicular to the leaf 
surface or somewhat oblique, but a few were curved or even tortuous. 
Fig. 5. — Shows the haustorium of 31. pcllata penetrating through two 
sclerenchyma fibres (comp. oc. No. 2). 
The penetrating power of the haustorium is best realised in examining a 
transverse section, in which the thickness of the walls of the sclerenchyma 
fibres is most evident (Fig. 5). On the upper surface of the leaf on which 
the fungus is able to flourish, the distance from the leaf surface to the first 
chlorophyll-containing cells is often as much as 130 /x. 
The other genera of the Ferisporiaceae are poorly represented in South 
African species in the National Herbarium. Two of these fungi, ZuJcalia 
transvaalensis and Phaeodimeriella ca^ensis, on careful study proved to be 
parasitic on Asterlna sj)p., the hyphopodiate mycelium described for these 
two species being that of the host, and the mycelium actually belonging to 
them forming a weft of pale fine hyphae investing the Asterlna mycelium. 
Zukalia transvaalensis should therefore be placed in the genus Perisporiitnu 
