PENICILLIUM GLAUCUM. 1ST 



blue grapes, even if they are attacked when ripe. Some species 

 of Botrytis contain an enzyme which destroys cellulose. 



It may be mentioned in conclusion that the leaves and 

 stems of tobacco plants are subject to the attack of certain 

 species of Botrytis, which bring about decay. 



2. Fenicillium glaucum (Fig. 33). 



A mould which is far more widely distributed in the fer- 

 mentation industries, especially in green malt, is Penicillium 

 glaucum. It forms a felt-like mass on the substratum, at 

 first white, then greenish or bluish-grey, and it spreads with 

 great rapidity. The mycelium consists of transparent branched 

 and divided filaments, which, when immersed in liquids, are 

 liable to swell somewhat irregularly. From these filaments 

 the conidiophores (A, Fig. 33) rise perpendicularly. They 

 consist of elongated cylindrical cells, the terminal cell of 

 which is soon arrested in its growth, and forms a thorn-like 

 point ; the cell immediately below throws out one or more 

 opposite branches, rising up close to the terminal cell, each 

 consisting, like this, of a single pointed cell. In more vigorous 

 individuals the branches may again ramify (compare A, upper 

 half), or similar branches may also spring from the next cells, 

 and these also ramify and become pointed as described above. 

 In this tuft of branches each pointed cell (sterigma) breaks up 

 into a series of spherical conidia, and finally the tuft carries 

 a large number of conidia, arranged in series, which, when 

 ripe, are readily scattered. These round, smooth conidia give 

 to the patches of mould their greyish-blue colour ; when they 

 fall upon moist surfaces, they are able to germinate at once. 

 According to Cramer, they are very resistant to higher tem- 

 peratures. 



In culture experiments with this fungus, Brefeld made 

 the interesting observation that Penicillium may occur under 

 certain conditions with an entirely different form of growth. 

 He enclosed cultures of this mould on slices of coarse, non- 

 acidified bread, between glass plates, and allowed the culture 

 to develop whilst excluding air as far as possible. Pairs of 

 short thick branches then grow on to the mycelium, which 



