CHAPTER XIV 

 CHLOROPHYCEAE. GREEN ALGAE 



Since the Chlorophyceae furnish our best illustrations of the 

 evolution of the plant body, the origin and development of sex, and 

 also the beginning of alternation of generations, they occupy a 

 prominent place in any well-planned course in the morphology of 

 plants. 



They are found in both fresh and salt water, but are most abun- 

 dant in fresh water. The ponds, ditches, and rivers of any locality 

 will yield an abundance and variety both of the unicellular and the 

 multicellular members of this group. Most of the forms are inde- 

 pendent, but there are epiphytic, endophytic, and saprophytic 

 species. The larger forms and those which grow in tufts or mats are 

 readily recognized in the field. Many of the smaller forms are 

 attached to other water plants. Drain the water plants and then 

 squeeze them over a bottle. The sediment is likely to contain a 

 variety of unicellular and other small algae. 



Many of the genera are easily kept in the laboratory. It is not 

 necessary to have very large aquaria. Ordinary glass battery jars 

 holding about a gallon are good for most forms. Jars holding two 

 gallons will be as good or better. For some cultures which are to 

 be kept for a long time, glass jars with ground tops and covers are 

 very desirable. Put about an inch of pond dirt in some, clean sand 

 in others, and in still others use a gravel bottom. 



When possible, use the water in which the algae were growing, 

 since very few take kindly to a sudden change of water. If the 

 material has been brought to the laboratory in a very small quantity 

 of water, fill the jar about two-thirds full with tap water. Let the 

 water run for two or three minutes before you fill the jar, sirice the 

 water standing in the pipes is injurious, or even fatal to most algae. 

 Add water occasionally, only a little at a time, to compensate for 

 evaporation. If the water has evaporated until the jar is about 



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