7 2 COMMON LI VER IVOR T. 



the walls between the air cavities; also the disposi- 

 tion of the surrounding tissue. 



Cut a rather thick vertical section a little to one side 

 of the center of an immature receptacle, and notice 



g. The chlorophyll cavities,with their chlorophyll cells. 



h. The much larger antheridial cavities, which are 



quite likely to be empty, or may contain the 



membranous remains of the antheridial sac, or may 



be more or less filled with 



3. The antheridium with its paraphyses j notice 



a. The shape of the antheridium. 



b. The pedicel by which it is attached to the bot- 

 tom of the cavity. 



c. The structure of the wall, brought into view by 

 focusing on the part nearest the eye. 



d. The wall as seen in optical section, only a single 

 cell in thickness. 



e. The uniform contents, consisting of very small 

 squarish cells, filled with colorless protoplasm. 



/. The several unicellular paraphyses surrounding 

 the base of the antheridium, and not much longer 

 than its pedicel ; best seen when the antheridia are 

 young. 



g. That the antheridia are younger toward the margin 

 of the head, and older toward the center. 



h. Draw an antheridium with its paraphyses. 



4. The antherozoids ; if the section just examined be from 

 a freshly gathered specimen, the contents of many of 

 the antheridial cells will have escaped into the water of 

 the slide 6 ; notice 



5 An excellent way to obtain antherozoids for examination is to place 

 a small drop of water on a slide and hold a freshly gathered head in it for 

 a few moments, when, if the antherozoids are ripe and abundant, they 

 will make the water milky. 



