ANATOMICAL STRUCTURE AND VITALITY. 61 



family, the coat of the seed remains entire, thus prevent- 

 ing the expansion of the cotyledons ; in such cases the 

 plumule is protruded in a manner analogous to mono- 

 cotyledons, the acorn remaining entire long after the 

 young plant has become established. 



The embryo of all flowering plants partakes of one of 

 the above characters, and hence come two grand divisions 

 of the vegetable kingdom — Monocotyledons and Dico- 

 tyledons. Plants produced from these two kinds of 

 seeds are readily known by the structure of their stems, 

 and veins of their leaves, which will now be described. 



III. ANATOMICAL STRUCT UEE AND VITALITY. 



CONSTRQCTION. 



When examined by the aid of the microscope, the sub- 



FiG. 9. 



stance of which plants are composed is found to consist 

 of what is called cellular and vascidar tissue. The 

 former is a conglomeration of thin membranous vesicles, 

 united to one another, forming cells hke those seen 

 in wheaten bread (fig. 9, a), endowed with the power of 

 producing their like, and by that means increasing 

 the bulk of the plant. The normal form may be con- 



