THE BHYOPHYTES. 



175 



free from wetting for several days ; after a few minutes 



transfer the drop of water to a slide by inverting the 



antheridium on the slide. It is to 



be remembered that motile an- 



therozoids can be found only at 



the seasons of the year when the 



plants are at the right degree of 



maturity. 



Compare the upper and lower 

 surfaces of the male receptacle 

 with the corresponding surfaces 

 of the thallus. 



6. Study the structure of the 

 archegonial branch. With a mag- 

 nifying glass examine the grooves FlG 102 ._c e iis from Mar- 

 on the under side of the receptacle. 

 Imbed a receptacle in pith, make 

 vertical sections, and examine with 

 high power for archegonia. These 

 are shaped something like a flask 

 with a long neck. The archegonia 

 may also be obtained for examina- 

 tion by scraping out the contents 

 of one of the grooves into a drop 

 of water. Draw an archegonium, 

 showing clearly its stalk, body, and neck. Try to make 

 out the internal structure of an archegonium, studying as 

 many specimens of different stages of development as can 

 be found. Crush under the cover glass some of the fully 

 matured archegonia ; study the spores and elaters. The 

 latter are marked by delicate spiral bands. Draw both. 

 Crusli a ripe archegonium on a glass slip without mois- 

 ture. Examine under high power, and Avhile looking 

 through the microscope let some one breathe gently on 

 the mass. What happens to the elaters ? What mecharii- 



chantia polymorpha. A, 

 an elater ; A', part of same, 

 showing spiral cell walls ; 

 B, a cell from the plant 

 body showing pitted mark- 

 ings of the cell wall. This 

 is the first instance in as- 

 cending the scale of plant 

 life of a structure very 

 common in the higher 

 plants ; C and D, rhizoids, 

 such as are seen at the 

 base of E, Fig. 98. (After 

 Sachs.) 



