THE MOULD-FUNGI. 103 



branches, which rise up close to the terminal cell and, like this, 

 consist of one pointed cell. In more vigorous individuals the 

 branches may again ramify (compare Fig. 27 A, upper half), 

 or similar branches may also spring from the next cells, and 

 these again 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'S researches they are very resistant to 

 higher temperatures. 



In culture experiments with this fungus, BREFELD made 

 the interesting observation that Penicillium can occur under 

 certain conditions with an entirely different form of growth. 

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

 non-acidified bread, between glass plates, and allowed the 

 culture to develop while excluding air as far as possible. 

 There then appear in pairs on the mycelium short, thick 

 branchings, which become entwined (-6, upper half); one part 

 of this spiral throws out short, thick filaments (C), whilst 

 the hyphal thread carrying the spiral develops numerous fine 

 branches, which envelop the spiral and form a covering (D), 

 consisting of an inner solid and an outer felt-like layer; the 

 inner cells are gradually coloured yellow, and the outer loose 

 cells are cast off. In this small yellow ball sclerotium a 

 formation of swollen cells (E, F, GT) gradually takes place 

 by the continued branching of the above-mentioned spiral 

 filaments, and in each of these new cells eight large and 

 lenticular spores are produced, which have a circular furrow 

 on the margin, and three or four slight ridges on the outer 

 membrane (Exosporium}. After the collapse and absorption 

 of all the remaining elements of the interior the spores are at 

 last set free, and the small yellow ball is then filled with 

 the spore- dust. The entire development requires six to eight 

 weeks. The sclerotia may be preserved in a dry state for 

 several years without losing their power of germination. 

 When the spores (N) are sown, the exosporium bursts open 



