﻿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/iara, and its 

 structure is more easily made out. 



[The Ckaracea, or plants belonging to the genera Chara and 

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

 class of Alga, which 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 rhizoids. 



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 (leaflets] ; their 

 form, size, &c. 



c. The oogonia and autheridia ; their position, 

 size, form, colour. 



Draw a portion including two or three internodes. 



B. HlSTOLOGlCAL 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. 



