312 



I'LANT STUniES 



cells more or less modified for conduction. Above these 

 the dorsal region is organized into a series of large air cham- 

 bers, into which project chlorophyll-containing cells in the 



Fig. 2,S6. Marchantla pnlyiiinrlilia, a rommon liviTwnrt : 7, Ihalhis, witli rhizoids, 

 bearing a mature arclirf;ciiiial liraiidi ( r'l and KrviTal yniiiiKcr ours («, b, c, ./, f l; 

 2aiid3, dorsal and vmtral views nf arclic>£;niual (iisli; 7, and ,>;, young sporophyte 

 (spnrogonium) embryos; i;, more nialiire spore i^'oninni still within enlarged venter 

 of archegoiiiiini; 7. mature sporogoniinn diseliargiug s]>ores; s, tbree s]»ores and 

 an elater. — Aller Kn^-. 



form of sliovt Id'tiiii'hing liltiiiieiits. Ovcran-liini;' tlie ;iir 

 clia.iidiers is the ilorstil ejiidcfiiiis, and ])iiM-ciiig tliroiio-li it 

 into each a.ir cliadidM'r is a coiispicuous tiir |i(ii-c (Fil;'. 'is;!, /.'). 



