62 BOTANY. 



perhaps from four to five, in the sunflower a larger number. 

 In these plants the colored areas on a cross-section of the stem 

 are situated in a concentric ring which separates more or less 

 completely an outer ring of the stem from the central portion. 

 If we now split portions of the stem lengthwise we see that these 

 colored areas continue throughout the length of the stem, in 

 some cases even up to the leaves and into them. 



108. Arrangement of the tracts in the corn stalk. If we 

 cut across the stem of a corn plant which has been in the solu- 



Fig. 51. 

 Bioken corn stalk, showing fibro-vascular bundles. 



tion, we see that instead of the colored areas being in a con- 

 centric ring they are irregularly scattered, and on splitting the 

 stem we see here also that these colored areas extend for long 

 distances through the stem. 



Exercise 25. 



109. To demonstrate the tracts in stems and petioles. Take leaves of a 

 calla lily, or of a caladium, which grow in conservatories, and good leaves 

 of stored celery, with long petioles. Other leafy shoots which are more 

 accessible may be used, if desired. Place the ends of the petioles, or the 

 shoots, in a solution of fuchsin, or in red ink. in the course of an hour (they 

 may be left in a longer time if necessary) observe the petioles and leaves. 

 Can any of the color be seen without cutting into the stem ? (Where the 



