168 



A TEXT-BOOK OF BOTANY 



epidermis there are several layers of colorless cells; above 

 these there is a series of large air-chambers into which 

 project the curious cells containing the 

 chloroplasts; and forming the dome-like 

 roof of each air-chamber is the upper 

 epidermis, pierced by a single air-pore 

 in the center of the roof of each cham- 

 ber. Each air-pore resembles a little 

 chimney, built up with several tiers of 

 cells. The rhombic areas seen on the 

 surface of the body are the outlines of 

 the air-chambers, and the minute open- 

 ing in the center of each is the air-pore 



FIG. iw.- Marchantia: ( F1 S- 162 ) This arrangement of cells 

 rhombic areas on up- containing chloroplasts exposed in air- 

 chambers that communicate freely 



chambers), each one through 

 pierced by an air- 



pore After SACHS, air-pores 

 suggests 



the same general mechan- 

 ism for plant work as that B 

 described for leaves, with 

 their internal atmosphere 

 and stomata (13). 



A remarkable fact con- 

 nected with the Marchantia 

 body, as contrasted with 

 that of the Thallophytes, 

 is that it produces no 

 spores. However, provi- 

 sion for rapid multiplica- 

 tion is made by the pro- 

 duction of peculiar repro- 

 ductive bodies that are 

 developed in little CUBE on 



ttie cups 



1 



FIG. 163. Marchantia: A, thallus bear- 

 ing little cups containing reproduc- 

 tive bodies, and an antheridial branch 

 with its disk, as well as some very 

 young antheridial branches; B, section 

 through antheridial disk, showing the 

 sunken antheridia. After KNY. 



