108 PRACTICAL BOTANY. 



Nitella in water. Find chlorophyl bodies that are under- 

 going division ; they are recognized by constrictions at 

 the middle of the cells. Draw. 



6. Cut off the end of a young internodal cell and press 

 the protoplasmic contents out into a drop of water on a 

 glass slip. Examine with high power. Describe the 

 changes that occur as the cell contents mix with the 

 water. Do you recognize starch granules ? Use iodine 

 solution if necessary. Notice also numerous large and 

 small masses of proteinaceous matter floating in the 

 colorless protoplasm. Do not confound these with the 

 chlorophyl bodies. 



7. Dissect a terminal bud with needles and mount in 

 water. Run iodine solution under the cover glass. Find 

 the apical cell. Has it more than one nucleus ? Observe 

 the cells below the apical cell and see, if you can, how the 

 nodes, internodes, and leaves result from the division and 

 subdivisions of the apical cell. Draw. The apical cells 

 of Chara and Nitella have been favorite objects for the 

 study of the division of the cell on account of the large 

 nuclei and the clearness of the successive steps in their 

 differentiation. The plant increases in length by the 

 division of these apical cells. In this respect there is a 

 decided advance over plants in which any of the cells 

 may divide. 



Place a healthy plant in water in the sunlight. Notice 

 the number and measure the lengths of the internodes. 

 After some days notice if there has been any increase in 

 the number of internodes and in their lengths. 



8. Study the antheridium. It may be recognized by 

 the naked eye or a magnifying glass as an orange-colored 

 sphere. (Fig. 60, .#.) The color is due to a pigment which 

 results from the ripening of the chlorophyl bodies that line 

 the inner surface of the cells. Notice under high power 

 several circular cells on the surface. There are eight of 



