THE GEEAT GKOUl'S (iF BKYOPIIYTES 



113 



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. 97. Jfrtrchantia polymorpha, a common liverwort : i, tliallus, witli rhizoids, 

 bearing a mature arcbegonial branch if) and 6e\eral younger ones (a, b, c, d, e)\ 

 2 and J, dorsal and VL'iitral views of archegonial disk; U and 5, young sporophyte 

 (sporogonium) embryos; 6. more mature sporogonium still within enlarged venter 

 of archegonium; 7, mature sporogonium discharging spores; .S, three spores and 

 an elater — After Kn v. 



form of short brandling filaments. Overarching the air 

 chambers is the dorsal epidermis, and piercing through it 

 into each air chamber is a conspicuous air pore (Pig. 94, B). 



