142 LABORATORY AND FIELD EXERCISES 



c. Comparisons. How does the gametophyte of the spruce 



compare with those of the cycads ? Has there been 

 any further reduction in the archegonia ? 



d. Draw your section and label its parts correctly. Draw 



a single archegonium enlarged. Label. 



3. The seed and embryo. 



a. Cut median long sections of seeds of pine or spruce 



which have been softened in water. Study the sec- 

 tion of the seed which shows the embryo most plainly. 



b. Seed structure. Compare the structure of the seed with 



that of the ovules just studied. What structures of 

 the ovule remain in the seed ? What structures are 

 changed ? From what did the embryo arise ? 



c. Embryo structure. Compare the structure of the embryo 



with that of seeds previously studied. Do you find 

 hypocotyl and cotyledons ? 



d. Draw your section and label the parts of both seed 



and embryo. 



4. Seed germination. Study seeds in process of germination 



and make sketches to illustrate these phenomena: 



a. Exit of the embryo from the seed. What part of the 



embryo emerges from the seed first ? Do any parts 

 remain in the seed ? 



b. Exit of the embryo from the soil. How is this effected 



and by what parts of the embryo ? Compare this 

 stage with a similar stage in peas illustrated in 

 Part I of the text. 



c. Adjustment of the embryo to light and soil. Compare 



with peas as above. 



d. Make appropriate drawings to illustrate a, b, c, above. 



5. Life history. Write a graphical life history of the spruce, 



indicating the main stages of the gametophyte and 

 sporophyte generations. 



