CHAPTER VII. 



MICROSCOPIC STRUCTURE OF HIGHER CRYPTOGAMIA. 



203. From those simple Protophytes, whose minuteness causes 

 their entire fabrics to be fitting objects for Microscopic examina- 

 tion, we pass to those higher forms of Vegetable life, whofee 

 larger dimensions require that they should be analyzed (so to 

 speak) by the examination of their separate parts. And in the 

 present chapter, we shall bring under notice some of the princi- 

 pal points of interest to the Microscopist, which are presented 

 by the Cryptogamic series ; commencing with those simpler Algae, 

 which scarcely rank higher than some of the Protophytes already 

 - described ; and ending with the Perns and their allies, which 

 closely abut upon the Phanerogamia or Flowering Plants. In 

 ascending this series, we shall have to notice a gradual differentia- 

 tion of organs ; those set apart for Reproduction being in the 

 first place separated from those appropriated to l^utrition (as we 

 have already seen them to be in the Characese) ; and the principal 

 parts of the E^utritive apparatus, which are at first so blended 

 together that no real distinction exists between root, stem, and 

 leaf, being progressively evolved on types more and more pecu- 

 liar to each respectively, and having their functions more and 

 more limited to themselves alone. Hence 

 we find a differentiation, not merely in j-m, us, 



the external form, but also in the inti- 

 mate structure of organs ; its degree bear- 

 ing a close correspondence to the degree 

 in which their functions are respectively 

 specialized or limited to particular actions. 

 Thus in the simple Viva (Fig. 104), what- 

 ever may be the extent of the frond, every 

 part has exactly the same structure, and 

 performs the same actions, as every other 

 part ; living /or and by itself alone. In 

 Batrachospermum (Fig. 110), we have 

 seen a definite arrangement of branches 

 upon an axis of growth; and while the MesogUm vermiciOaris. 

 branches are formed of simple necklace- 

 like rows of rounded cells, the cells of the stem are elongated 

 and adhere to one another by flattened ends. This kind of dif- 



