82 LABORATORY AND FIELD EXERCISES 



Sketch one or two stages in the formation of female 

 gametes. Label accurately. 



b. Male gametangia and gametes. If material is available, 



study the male gametangia and gametes as described 

 and figured in the text. Sketch stages demonstrated, 

 and label. 



c. The zygote. Study the zygote of (Edogonium. Is it 



adapted, by its cell structure, for carrying the plant 

 over an inclement period ? Note its form and con- 

 tents. Draw. 



d. Asexual reproduction. The asexual reproductive process 



is difficult to demonstrate with beginning classes and 

 should be studied from the text and figures. 



e. Life history. Write a graphical life history of (Edogo- 



nium similar to that outlined for Spirogyra. How is 

 this history adapted to seasonal changes ? 



GENERAL STUDY OF FRESH-WATER ALG.E 



1. Examine water containing free-floating algae, or algse 



attached to objects covered by water. If algse are 

 scraped from surfaces, they should usually be separated 

 on the slide with needles or by gently tapping the 

 cover glass with needles. Mount in fresh water and 

 examine first with low power. 



2. Form and structure. Note the number and kinds of algte 



living together in one place. How many distinct kinds 

 or species of algre can you distinguish in the water you 

 are examining ? Are there unicellular forms ? many- 

 celled forms ? Have any species the power of movement? 

 Note differences in the form or color of the chloroplasts 

 in different species. 



3. Reproduction. Are any of the species that you are ex- 



amining reproducing either vegetatively, asexually, or 



