XIII.] MOULDS. 419 



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

 hand we have the hyphos, constituting the vegetative part of 

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

 which is purely repi'oductive. 



The hyphae again, are either siibmej'ged 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 hyphse, on the other 

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

 bear the reproductive organs, may be compared to the 

 shoot^ or leafy stem of the higher plants. 



Besides the purely asexual organs of reproduction above 

 described, Penicillium also occasionally produces structures 

 which appear to represent sexual organs, though their func- 

 tional activity is in this case more than doubtful.. A com- 

 plex truffle-like fruit is produced from them, but these 

 phenomena will be more easily studied in another mould, 

 the Eurotiym Aspergillus glauciis. 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 repro- 

 duction there is little difference from Penicillium. All the 

 hyphae are stouter, and the conidiophores 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 sexual fruits will begin to make their appear- 

 ance. They may be recognized 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 



27 — 2 



