PART OF MOVEMENT OF LIQUIDS IN PLANTS. 63 



shoots remain in the colored liquid for a day, or even for a less time, portions 

 of the leaves will show the color.) Cut across the stems, and describe the 

 location of the colored areas. Split the petioles or stems and trace the colored 

 tracts. Compare their location in the calla and the celery petiole. 



110. To observe the texture of these areas in a celery petiole. — Take fresh 

 but rather old celery leaves (from stored celery if in the winter). Break the 

 petiole apart. Is the broken part ragged ? Is there any difference in the 

 texture or toughness of the petiole shown by any portions " stringing " out ? 

 Describe the location of these strands. What are they ? Have they any re- 

 lation to the colored areas or tracts in the petiole which was in the red ink ? 

 Break apart in a similar way a petiole which has been in the red ink. 

 Compare. The celery represents a dicotyledenous plant. 



111. The strands in a dead corn stalk. — Take a dead corn stalk (they are 

 easily obtained in the autumn or winter from the fields). Cut through the 

 outer harder portion of the stem. Break it. Compare carefully with the 

 broken celery petiole. The corn stem represents a monocotyledonous plant. 



112. There are definite courses through which the liquids 

 rise. — We thus see that instead of the liquids passing through 

 the entire stem they are confined to definite courses. Now that 

 we have discovered the path of the upward movement of water 

 in the stem, we are curious to see what the structure of these 

 definite portions of the stem is. 



Demonstration 21. 



113. Structure of the fibrovascular bundle. — Make quite thin cross-sec- 

 tions of the stem it is desired to study, and mount in water for microscopic 

 examination. Permanent mounts may be made in Canada balsam by those 

 who understand the method. Or mounted preparations may be obtained, 

 which will preserve for future use. Let each pupil examine cross and longi- 

 tudinal sections of a dicotyledon and of a monocotyledon, making out 

 clearly the different groups of tissues, and the kinds of cells composing them. 

 Paragraphs 114-123 may be used as a guide. The description is here made 

 from the castor-oil bean, and the illustration from the sunflower to represent 

 the dicotyledon, while the corn stem is used to illustrate the monocotyledon. 

 It will be no disadvantage for the teacher to use other plants than those em- 

 ployed here for the demonstration. 



114. The bundles in a dicotyledon.— To illustrate the structure of the 

 bundle in one type we may take the stem of the castor-oil bean. On examin- 

 ing these cross-sections we see that there are groups of cells which are denser 

 than the ground tissue. These groups correspond to the colored areas in the 

 former experiments, and are the vascular bundles cut across. These groups 



