224 



PLAA^T LIFE. 



sarily ruptured to permit the escape of the sijores, being 

 often disi'laced in the de\'e]opmcnt of the sporangium, so 

 that at maturit\' it is jAartially free. 



Fig. 223. — .\ mildew ( A rrJ"///;t' t('/;////;/v//.v). slmwing tilt mycelium ramifying over a 

 l?it oi leaf, witli erect spore-bearing brandies and globular fructifications, containing 

 asci. Magnified about 175 diam. — .^fter I'tdasne. 



318. Compound sporangia. — Simple sjjorangia occur only 

 among the lower jjlants. In the higher plants, including 

 the mossworts, fernworts, and seed 

 ^^v plants, the sporangium is always 

 SX/ compound. 



319. Development. — Compound 



^ sporangia ma\' he deN'cloped either 

 from superllcial or fj-om internal 

 FtG. 224 -A cluster of asci from cglls. As a conseuueuce, the mature 



the interior of the fructihcatioii ' 



ofamildew'yrry.w>/:f/y..r,jc-/.-/i sporangia will lie either free or fnore 



similar to those shown m hg. 223. ^ ^ 



Each ascus contains four spores, gr leSS Cll. loscd withill the tissUCS of 



Magnihed 200 diain. — After De- 



^">'' the organ 1)\' which thev are borne. 



A superficial cell ma\' enlarge so as to protrude from the 

 surface, and di\ide into two parts, of whii h the uiipcr cell 

 develops into thes[)orangiiim proper, aifd the h.iwer cell into 

 its stalk. According to this metliod of de\"elopment the 

 s[)orangiuni is a surface appendage, and ma\- be looked upon 



