436 ELEMENTARY BIOLOGY. [CHAP. 



in the water; and that, except so far as the reproductive 

 organs are concerned, there is a morphological differentia- 

 tion of organs, unaccompanied by a corresponding phy- 

 siological differentiation. 



Nitella is a rarer plant than C/iara, and is simpler in 

 structure, its axis being devoid of the cortical layer. In 

 other respects, however, it is very similar to C/iafa, and its 

 structure is more easily made out. 



[The Characccp^ or plants belonging to the genera Chara and 

 Nitella, are found in all parts of the world, and belong to the 

 class oi Alger, vi\\\Q}i\. also includes the sea-weeds.] 



LABORATORY WORK. 



A. Naked-eye characters. 



Note the slender elongated axis {stem) ; the whorled 

 appendages {leaves); the nodes and inter nodes ; the shortening 

 of the latter towards the apex of the stem ; the 7-hizoids. 



a. The roots ; small; serving chiefly for attachment, 

 the plant getting most of its nutrition, through 

 other parts, from matters dissolved in the water. 



b. The leaves ; their sub-divisions {lea/lets) ; their 

 form, size, &:c. 



c. The oogonia and antheridia ; their position, 

 size, form, colour. 



Draw a portion including two or three internodes. 



B. Histological structure. 



a. The stem. 



I. Examine the outside of a fresh internode with a low 

 power, or pocket lens, to see the spirally-arranged 

 cortical cells. 



