2^0 



CHARACE.E. 



not alternate like the whorls of primary leaves (Fig. 200,'C-E, /3). Each leaf begins 

 with a node (the basal node ^), by which it is united with the stem-node, just 



Fig. 199.— Longitudinal section tlirough tlie biul of Cliara fragiLis ; in A the contents of the cells have been removed ; in 

 B the fine-grained substance is protoplasm, the larger granules are chlorophyll ; the formation of vacuoles is shown ; in C the 

 contents of the cells have been contracted by iodine solution (X500). 



Fig. 200.— Leaves oi Chara fragilis ; a terminal cell, b penultimate cell of a leaf; z internodal cell; w cells of the leaf- 

 node ; y" mother-cell of a leaflet and of its basal node ; from it arise v and u (the uniting cell), br the basal node which 

 produces four simple cortical lobes and jS the leaflet. A and C in longitudinal section, B an entire young leaf, external 

 view, with the 'stipule' J and its descending cortical lobe of the stem sr ; D external view of the middle part of cin older leaf, 

 though still young ; E transverse section of a leaf-node, of the same age as D. 



like each leaflet with its primary leaf. These basal nodes are the points of origin 

 of the formation of the cortex which, in the genus Chara, covers the internodes 



* The cell x in Fig. 199, A, may however be considered also as the first intern ode of the leaf; 

 then the nodes of the stem would consist only of the middle plate m, which is bisected by a longi- 

 tudinal wall. A comparison with Muscineoe and Vascular Cryptogams leads however also to the 

 supposition that the whole group of cells ;c S r" r" which proceeds from y belongs in common to 

 the stem and leaf: 



