23 



In the foreign Ch. stelligera neither stipules nor cortex are devel- 

 oped, but three small cells protrude slightly at the base of the leaf. 

 In Ch. ceratophylla there are frequently three double stipules at the 

 base of each leaf, see Fig. 31, showing the short inflated double stip- 

 ules, camera drawn, x 25 diam. 



In the Nitellce there is no de- 

 velopment of cortex or stipules, 

 but in a few species of Nitella we 

 find accessory leaves arising from 

 a true verticil. These accessory 

 leaves are more simple than the 

 true leaves; they produce no nodes 

 or fruit, and do not subdivide. 



We find these accessory leaves 

 numerous in our N. hyalina and 

 N. clavata. In the genus Tolypella 

 fruiting organs, both sporangia and 

 antheridia, spring from the basilar cells of the leaf in the verticil, 

 both external and internal, often in large numbers. 



Fig. 30. 



Fig. SI- 



LEAVES. As the cell which is to form the leaf protrudes from its 

 basilar node, it divides very early into a series of cells which are des- 

 tined to form the nodes, internodes and tip. 



The cells of the tip of the leaf attain their full size soonest and the 

 disproportion of size in very young leaves is very great. These 

 apical cells of the leaf may always be distinguished by the absence of 

 any formation of nodes ; consequently, they are devoid of bracts, re- 



