XIII.] MOULDS. 419 



of the body of the plant into distinct organs. On the one 

 hand we have the hyphae, constituting the vegetative part of 

 the organism, on the other the conidia, the function of 

 which is purely reproductive. 



The hyphae again, are either submerged or aerial. The 

 former may be described from a purely physiological point 

 of view as the root, being characterized by the two func- 

 tions of attaching the plant to the substratum, and of taking 

 up food-material from it. The aerial hyphas, on the other 

 hand, in so far as they absorb oxygen from the air, and 

 bear the reproductive organs, are analogous to the shoot, or 

 leafy stem of the higher plants. 



Besides the conidial organs of reproduction above de- 

 scribed, Penicillium also occasionally produces reproductive 

 structures of another kind, the development of which is 

 far less simple. A complex truffle-like fruit (cleistocarp) is 

 produced from them, but these phenomena will be more 

 easily studied in another mould, the Eurotium Aspergillus 

 glaucus. Though less abundant than Penicillium, this plant 

 is of very common occurrence, especially on such substances 

 as preserved fruits. Apricot jam, for example, may be used 

 for growing the Eurotium upon. In the vegetative structure 

 and the asexual reproduction there is little difference from 

 Penicillium. All the hyphae are stouter, and the conidio- 

 phores are unbranched. Each head of conidia can be 

 distinguished separately with the naked eye, which is not 

 the case with the more minute Penicillium. After the 

 fungus has been growing for some weeks the cleistocarps 

 will begin to make their appearance. They may be recog- 

 nized as small round yellow bodies, easily distinguished 

 from the heads of conidia by their colour and their sessile 

 position. The development of these fruits is somewhat 

 complicated. A branch grows out from one of the hyphae, 



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