Paet II 



TYPE STUDIES PRECEDED BY THE STUDY 

 OF THE PLANT CELL 



THE PLANT CELL, ITS STRUCTURE AND 

 REPRODUCTION 



56. The cell structure of the Spirogyra filament (App. 6).* 



A. Examine living material. What is its habit of growth, 

 floating or attached ? What is its color ? How does it feel 

 between the fingers ? Note that it is made up of filaments, ' 

 or threads. 



B. Mount two or three filaments in water under a cover glass. 

 Examine with l.p. (low power). Are the filaments branched ? 

 Do they vary in thickness ? Note the cross partitions that 

 divide the filament into parts called cells. Draw the outline 

 of a filament under l.p. 



C. Study a filament under h.p. (high power). Do the cells 

 vary in length ? How much ? Select favorable cells and 

 focus on the cross partitions between them to determine 

 their geometrical form. What is the form of the entire 

 cell ? Draw a group of two or three cells on a large scale, 

 noting : 



1. The transparent cell walls bounding the filament and 

 forming the cross partitions. 



* To THE Instructor : The exercise outlined in Sec. 56 is an excellent one to 

 acquaint the student with the use of the compound microscope and the interpre- 

 tation of the geometrical form of structures by focusing up and down. If the 

 instrument has not been used before, the student may be made familiar with its 

 parts and their manipulation as described on pages 10-14, under the heading 

 " The Construction and Use of the Compound Microscope." 



76 



