114 MAN0AL OF NATURE STUDY. 



brancli, of cherry, peach, sycamore, bean. Have 

 pupils count the rings of growth in stumps of trees 

 and cross sawed timber. Do these rings represent 

 periods of growth? Can we then form some notion 

 of the age of the tree? By way of contrast, make 

 a collection and study of endogens. As in exogens 

 collect bundles of cuttings three or four inches long. 

 Examine cross sections to see if the bark is the same 

 as that which covered the exogens. Can you in 

 any way pound or rub the bark of a cornstalk loose 

 as you did the willow bark? Can you the grass 

 bark? The wheat bark? Sugar cane? The 

 palm? Pond weed? Cat tail? Indian turnip? 

 Banana? Lily? Pineapple? Any of the rushes? 

 Fish pole ? Do you find in any of these cuttings 

 the fibre bundles arranged in rings around a cen- 

 tral pith ? Compare with oak, box-elder or bean in 

 this respect. Make drawings of cross sections of 

 endogens, alternated with exogens so as to get the 

 distinction fully fixed on the mind. Plant a few 

 acorns, beans, peas, beech nuts in same dirt 

 with com, sugar cane, wheat, and notice difference 

 in number of seed leaves as they begin to come 

 through the dirt. Those having two seed leaves 

 are called dicotyledonous plants, and those having 

 but one seed leaf monocotyledonous. To which of 

 these does corn belong? Apple? Is the walnut 

 exogenous or endogenous? How can you tell? 



