396 



THE NON-VASCULAR PLANTS 



FIG. 193. Riccia, a simple liverwort. 



the ancestors from which they sprang. Such fjrms began 

 the conquest of the land by plants and such forms are found 

 to-day among the liverworts. Such forms are said to be 

 amphibious, which means that they are capable of living 



both in the water and 

 on the land. 



The body of the 

 simplest liverworts is 

 a sort of plate of cells 

 having certain out- 

 growths beneath. 

 (See Figure 193.} 

 The commonest liver- 

 worts, however, such as are found on damp rocks in shady 

 places, have a more complex structure. An outline of this 

 structure as it ap- 



pears under the 

 microscope is 

 shown in Figure 



194. This is a 

 view which you 

 get by examining 



a thin Slice Of the FIG. 194. Section through the thallus of Marchantia. 



liverwort CUt Note t ^ ie large air c h am ber, a, under the upper epi- 



, , dermis; p is a permanently open pore; the chloro- 



thrOUgh from top p l as ts are principally contained in the cells of peculiar 



to bottom. The outgrowths, c, which arise from the bottom of the air 



i j f chambers. 



same kind of 



liverwort, as it appears to the naked eye, is shown in Figure 



195. The erect outgrowths are concerned with reproduc- 

 tion. The prostrate part is called the thallus, a word 

 which you met in studying thallophytes ; it describes a plant 

 body which is not differentiated into stems and leaves. 



