EXERCISE 36 

 IN WHAT PART OF THE LEAF IS THE CHLOROPHYLL ? 



Materials. Thin leaves, as those of moss, water weed (Elodea), pondweed (Potamogetori) ; 

 one or more compound microscopes, or a microprojection apparatus ; glass slides and cover glasses. 



Directions. If a sufficient number of compound microscopes are to be had, each pupil may per- 

 form this experiment independently, but if there is only one microscope, the teacher should arrange 

 a demonstration exercise. If the school possesses a microprojection apparatus, the specimen may be 

 shown to the entire class at once. 



Mount a very thin leaf in a drop of water on a glass slide, cover with the cover glass, and 

 examine first with the low power and then with the high power of the microscope. 



Does the chlorophyll color the leaf evenly ? Can you distinguish the rounded bodies which are 

 called chloroplasts ? Is there any chlorophyll in the leaf which is not in the chloroplasts ? Groups 

 of these chloroplasts and other substances are inclosed within transparent, thin walls. These are 

 the cell walls, and the spaces inclosed by them contain not only the chloroplasts but also the other 

 living material of the cell. The living material is so transparent that it will probably not be seen. 



Observe and describe carefully all that has been done. 



Additional problem. Is the upper or lower surface of ordinary leaves more green ? Is this true of 

 all leaves ? 



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