192 



CRYPTOGAMS 



315. A peritheciuni brok- 

 en open to show 

 the asci. 



^ 





tions are produced on the leaf surface, appearing to the 

 naked eye as minute rounded black bodies. These are 



the perithecia (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 

 tlie 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 through two stages of develop- 

 ment differing in the 

 method of spore bear- 

 ing. Penicillium, a very 

 common blue mold (Fig. 

 318), is an example. 



457. The Rusts. — Many Fungi un- 

 dergo remarkable transformations in the 

 course of their life history. This is very 

 marked in the case of the Rusts, of which 

 the common Rust of Wheat (Puccinia 

 graminis) may be taken for description. 



T^ • p . .1 -. T - P ^TTi 318. Sporophore 



It mtests the leaves and stems or \\ heat, Peniciiiiiun. 



Fruit of Asper- 

 gillus, with 

 asci (a). 



— Kny. 



316. Section of the 

 sporophore of 

 Aspergillus. — 

 Kny. 



