STUDY OF A BRYOPHYTE 



263 



371. Examination of a Liverwort. — The Thallus. The 



broad, flat, branching organ that forms the body of the 



plant is the thallus. Examine 



the end of each branch ; what 



do you find there ? Are the two 



forks into which the apex of the 



branches divide equal or un- 

 equal.'' Do you see anything 



in these forking apexes to remind 



you of the heart-shaped prothal- 



lium of the fern .' Are there any 



other points of resemblance 



between them ? Compare the 



growing end with the distal one ; 



does it proceed from a true root .' 



Notice that as the lower end dies 



the growing branches go on increasing and reproducing 



the thallus. 



Do you find anything like a midrib ? If so, trace it 



along the branches and 

 stem ; where does it end .■' 

 Does it seem to be formed 

 like the midrib of a dicoty- 

 ledon ? Hold a piece of 



•?' 



501. — Under side of an arche- 

 gonial receptacle enlarged. The 

 archegonia are borne among the 

 hairs on the under surface, which 

 is presented to view in the figure ; 

 /, a spore case. 



503. — A portion of the upper 

 epidermis of marchantia, magnified, 

 showing rhomboidal plates with a 

 stoma in each. 



the thallus up to the hght 

 and see if you can detect 

 any veins. Is it of the 

 same color in all parts, and 

 if there is a difference can 

 you give a reason for it ? Examine the upper surface with 

 a lens. Peel off a piece of the epidermis, place it between 



502. — Portion of a thallus bearing an 

 antheridial disk or receptacle, d, and gem- 

 mae..?, i'. 



