248 Olomerella cingulata and its Conidial Foniis 



eud of the culture tube and at the margin of the agar medium. By con- 

 tinuous subculturing on agar media and on sterilized potato tubers and 

 chilli pods the spore-bearing capacity is lost and the cultures remain 

 sterile, and on glucose-meat-extract-agar the growth is no more aerial 

 but matted and submerged. But if transfers from this sterile fungus 

 are made on sterilized chilli or potato stems, the growth is again fertile ; 

 the conidia are borne on tips of hyphae and in pink acervuli; and in 

 subcultures made on glucose-meat-extract-agar from this fertile culture 

 the mycelium is aerial, bears conidia and the growth resembles that 

 obtained originally from conidia planted on glucose-meat-extract-agar 

 but after three or four generations on the same medium it again becomes 

 sterile and confined to the substance of the medium. 



The mycelium is generally composed of two kinds of hyphae, one 

 very thin and the other very broad, closely septate and highly vacuolate. 

 At times intercalary vesicles are formed in the hyphae. The hyphae, 

 both broad and thin, often get fused together and form a network. 



The conidia are developed either in acervuli, as in Melanconiaceae 

 or on the tips of lateral branches of hyphae, as in Hyphomycetes. The 

 acervulus in cultures originates as an aggregation of hyphae forming a 

 stroma which from its commencement is brown like that of an acervulus 

 on the host plant. From the .stromatic cells hyaline basidia or conidio- 

 phores are developed from the tips of which conidia are produced in 

 succession. The stroma is usually without appendages but at times it 

 bears brown hyphae, generally flexuous, rarely rather stiff. These ap- 

 pendages have some remote resemblance to the setae of a Colletofrichum 

 acervulus. 



The spores, when sown in water, swell before germinating. At times 

 only a part of the spore is swollen, the unswollen end having a pinched-in 

 appearance. The germinating spore (Fig. 3) may become septate. The 

 germ-tube is developed from either end or from both the ends. Appres- 

 soria are formed at the tips of the germ-tubes. The germ-tubes occasionally 

 bear secondary conidia. Germinating spores may get fused together by 

 their germ-tubes or branches arising therefrom. 



In cultures, sclerotia are bften developed. They are generally small 

 and round but at times they have been observed to be as big as 1 mm. 

 in diameter. In cross sections these sclerotia are found either to be a 

 homogeneous mass of hexagonal or rectangular brown cells, or to be 

 slightly differentiated into cortex and medulla, the central cells being 

 large and thin-walled while the peripheral cells have a smaller lumen and 

 thicker walls. 



