LABORATORY AND FIELD WORK 407 



for the study of different organs and different portions of the life history. 

 It should be noted, however, that any other moss will differ in details 

 from the one described in the text. Moss spores can be germinated 

 without much trouble on moist bricks or tiles. Germination is slow 

 and may require several weeks. 



1. Examine a "moss plant." Of what parts is it composed? 

 In .what position does it grow ? Does the stem branch ? 



2. How are the leaves arranged? What is the form of a leaf, 

 as seen under a hand lens ? Can you see veins ? Are there differ- 

 ences between the leaves borne on different parts of the plant? 

 Draw a leaf in outline. 



3. What differences do you find between male and female heads 

 that is, the ends of stems or branches on which antherids and 

 archegones are borne? Tear apart a head of each sort. How are 

 the sex organs arranged? What other structures do you find in 

 the heads? Sketch an antherid and an archegone. How many 

 gametes are borne in each ? 



4. Examine different stages in the development of the asexual 

 plant. How does it secure its food? How is it attached to the 

 sexual plant ? What is the origin of the cap that is carried for a 

 time on the top of the asexual plant ? How do the spores escape 

 when they are ripe ? Draw a sexual plant to which an asexual 

 plant is attached, naming all the parts of each. 



5. Press out the spores from a ripe spore sac and examine them 

 under a microscope. What is their shape? Their color? 



6. If material is available, study and draw a portion of the pro- 

 tonema, which has grown from a germinated spore. This is the 

 first stage in the history of the sexual plant. Can you discover 

 how the leafy branches (commonly known as "moss plants") arise 

 from the protonema ? 



7. Find as many different kinds of mosses growing out of doors 

 as possible. In what sort of places does each kind grow? 



CHAPTER X 



For this, as for some of the preceding studies, it is not necessary to 

 use the species described in the text, though this is preferable. The 

 bracken fern is to be found growing almost everywhere. The leaves 

 and stems may be dried ; it will be well also to preserve parts of spore- 



