80 
J. W. Dowson, 
formation. The germ hyphae were always recognisable and became by 
increase in length and breadth, the main hyphae of the mycelium, which 
Fig. 25: Pleterosporium variabile. — Figs. 26—45: Heterosporiuvi echinulatum. — 
Fig. 46: Heterosporiuvi Betae. 
Fig. 25: Conidiophore heads of H. variabile showing articulations taken from 
herbarium material of Spinacia oleracea (x 600). — Fig. 26« and 26 b: Germinating 
conidia of H. echinulatum, a on salep agar after a few hours, b in water after 2 days 
(x 215). — Figs. 27 a —29: Showing the development of the conidiophores. (Figs. 
27«, 21b and 28 x 120. — Fig. 29 x 215. — Fig. 29 was drawn 6 days after 
fig. 28.) — Figs. 80—34; 35—37; 38, 39: Showing the formation and develop¬ 
ment of the conidia (x 215). In figs. 34, 37 the spores are not yet mature; but 
hanc yet to increase in length and breadth. In figs. 38, 39, the spores bave nearly 
reached their mature size. — Fig. 40: Conidia from a clean culture and mounted 
in lactophenol (x 215). — Fig. 41: Conidia from a diseased leaf and mounted in 
glycerine, showing unequal distribution of warts in young spores (x 215). — Figs. 42, 
and 43: One and the same conidiophore (Fig. 42 x 98, Fig. 43 x 120 and drawn 
2 days later). — Fig. 44: Mature conidiophore from hanging-drop-culture (x 98). 
— Fig. 45: Denuded conidia-bearing-hyphae showing the remains of the articu¬ 
lations (« x 98, b x 120, c x 215). — Fig. 46: Spores of H. Betae germinating 
upon dead portion of a wounded Beta leaf forming young mycelia (x 215). 
