BOTRYTIS CINEREA. 185 



night. Klein and Lindner found that in daylight the more 

 strongly refracted portion of the spectrum, the blue-violet 

 rays, hindered the formation of conidia, whilst it is encouraged 

 by the red-yellow rays. Under the constant influence of red- 

 yellow light, and in total darkness, the production of conidia 

 goes on both day and night. Under certain nutritive condi- 

 tions the conidia and ascospores develop short threads, from 

 which small, bright, round conidia are separated, either 

 directly or on bottle-shaped basidia. These conidia are not 

 capable of germination. If the mycelium has been cultivated 

 for some time on a solid substratum which it is incapable of 

 penetrating, short branches are formed, which by further and 

 repeated branching have the appearance of closely arranged 

 tufts or tasselled knots. They lie in close contact with the 

 substratum, and form the characteristic organs of attachment. 

 Under certain conditions this mould can assume a peculiar 

 dormant state, the sclerotium (skleros = hard) (see Fig. 32, a, 

 b, ss). The hyphal threads branch out freely, and the branches 

 intertwine themselves into a compact body of varying shape, 

 circular or fusiform, and of varying size ; the extreme ends of 

 the filaments are brown or black, and the ripe, solid sclerotium 

 thus consists of an outer black rind and an inner colourless 

 tissue. These bodies, which were described by de Bary under 

 the name of Sclerotinia Fuckeliana, occur as small black bodies 

 on the herbaceous parts of many plants, where they live as 

 parasites or saprophytes. They are capable, after a long 

 period of rest lasting at least a year of forming a new 

 growth. If the sclerotium is brought into a moist place soon 

 after it comes to maturity, the inner colourless branches 

 break through the black outer rind and develop into condio- 

 phores (a). If, however, the sclerotium is only brought into 

 a moist place after it has been at rest for some time, a large 

 tuft of filaments develops from the inner tissue, and these 

 shoot up perpendicularly, and finally spread out to a flat, 

 plate-shaped disc (6 and p s) ; the ends of the filaments are 

 arranged in parallel rows on the free upper surface of the 

 disc ; some of them remain thin, others swell up to club- 

 shaped asci, and each of these asci forms in its interior eight 

 oval spores (n). The mould has now entered upon the stage 



