26 



BOTANY AND PHARMACOGNOSY. 



which they grow. These areas become soft and spongy and are 

 always white at first. After a time hyphal branches, which are 

 more or less flask-shaped, rise above the substratum, and by a 

 process of division at the end of the' branch, or conidiophore, a 

 spore called a conidiospore is formed (Fig. 17, A; Fig. 18, A). 

 The process of division at the end of the conidiophore continues 



Fig. 18. Aspergillus, a yellow mildew. A, conidiophore with enlarged, more or less 

 spherical end, from which the fan-like series of chains of conidia arise; B-E, successive 

 stages in the development of perithecium; F, section through a nearly ripe perithecium; 

 G, groups of young asci; H, a ripe ascus with 8 spores. — ^A, after Kny; B-H, after DeBary. 



from below until a chain of conidiospores is formed. The conidio- 

 phore frequently branches, so that a fan-like series or group of 

 conidia or conidiospores is produced (Fig. 17, B; Fig. 18, A). 

 The conidia are usually some shade of green, but finally they may 

 become more or less brown. They are thin-walled, quite small, 

 and so light that they float freely in the air. If a colony is inhaled 

 it gives the sensation commonly called the " smell of mold." 



