MARCHANTIA POLYMORPHA. 63 



b. The flat, green, posterior* surface of the arche- 

 gonial branch, wanting in the antheridial. 



c. Pull a pedicel in two and notice the hairs pro- 

 jecting from a pair of grooves on its anterior 

 face. 



d. Make a transverse section of the antheridial ped- 

 icel and notice the outline, and the position 

 and form of the grooves. Draw. 



e. In a similar section of the archegonial pedicel 

 notice the outline, grooves, and the posterior 

 chlorophyll-bearing portion, with its row of air 

 cavities. Draw. 



The head of the antheridial branch, consisting of a 

 large receptacle and minute and inconspicuous anther- 

 idia imbedded in it ; notice 



a. The general shape of the receptacle. 



b. The particular outline of the margin. 



c. The broad radiating ridges on the upper and 



lower surfaces. 



d. The narrow wing-like margin, more easily dis- 

 tinguished by holding the head toward the light. 



f. The numerous scales on the ridges beneath, most 

 abundant toward the margin. 



/. Cut a vertical section and observe the rather 

 large oval cavities beneath the ridges ; each cav- 

 ity contains a single sac, antheridium, holding 

 the innumerable fertilizing bodies, antherozoids, 3 

 neither distinctly visible. If the antheridium is still 



8 1. e., the surface looking away from the axis of the stem and corre- 

 sponding to its upper surface. 



3 The antherozoids are far too small to be seen except with a compound 

 microscope ; they escape through openings in the upper surface, also too 

 small to be made out in this connection. 



