11 



CltYPTOGAMS 



olo. A perithecium brok- 

 en open to show 

 the asci. 



OO 



tions are produced on the leaf surface, appearing to the 

 naked eye as miuute rounded black bodies. These are 

 the 2}erithecia (Fig. 315) which in- 

 close the spore sacs. The perithecia 

 bear radial appendages. 



456. Aspergillus, a very common 

 fine mold on dry bread, cake, cheese, 

 preserved fruits, etc., should be men- 

 tioned here, since, though it is really 

 an Ascomycete, it would not be rec- 

 ognized as such at one stage of its 

 existence. On first appearing upon 

 the given substratum the mycelium sends up great num- 

 bers of erect branches ending in globular heads, from 

 which are produced spores in chains 

 radially arranged (Fig. 

 316). At a later stage 

 of its history the myce- 

 lium gives rise to small 

 rounded fructifications 

 inclosing the character- 

 istic spore sacs of an 

 Ascomycete. In like 

 manner other members 

 of this group are known 

 to pass tlirongh two stages of develo| 

 ment differing in the 

 method of spore bear- 

 ing. Penicillium, a very 

 common Ijlue mold (Fig. 

 318), is an example. 



457. The Rusts. — Many Fungi un- 

 dergo remarkalile transformations in the 

 course of their life history. This is verj- 

 marked in the case of the Rusts, of which 

 the common Rust of Wlieat (Puccinin 

 i/rami))ii<) mav Ije taken for description. 



', . ,. , ' , ^ J. ,,^, 'JIS S|iorophule of 



It iiuests liic lea\x\s anel stems of Wiieal, I'eniciliiiun 



17. Fruit ol Asper- 

 gillus, A\'ith 

 asci (o). 



— Kny. 



Section of the 

 sporttphore of 

 Aspergillus. — 



KXY. 



