STRUCTURE AND DEVELOPMENT. 25 



As in the case of the root-nodes the lower stem- 

 nodes in many species become thickened, owing to 

 the production of a very large number of small cells 

 containing reserves of starch. These also will be 

 referred to under the head of bulbils. 



The outgrowths from the normal stem-nodes consist 

 of (1) Branches; (2) Branchlets; (3) Stipulodes ; 

 (4) Cortex. 



The origin and order of development of these out- 

 growths will be best understood from Fig. 5 (p. 24), 

 taken from a species of Char a in which all are present. 



The normal branches are similar in 

 almost all respects to the main stem, and 

 present a non-limited growth. In the Charese there is 

 usually one branch produced at a node, in Nitella two, 

 and in Tolijpella several, but these numbers are subject 

 to variation. The normal branches originate in the 

 axils of the whorls, at the base of the oldest branchlet 

 or branchlets, see Fig. 5 B (p. 24). 



Branches of a special type are often to be met 

 with originating from the swollen nodes of old stems, 

 (PI. Ill, f. 3 EB), and occasionally from the root-nodes 

 of pro-embryos. These are styled by Pringsheim 

 " branches with naked base," and by Vines " embryonic 

 branches." In the corticate Charss they are charac- 

 terised by the basal segment of the stem and the 

 lowest whorl of branchlets being wholly or partially 

 ^corticate. 



These organs have by many authors 

 been styled " leaves," but this would 

 seem to be a misuse of words, since they do not appear 

 to present any analogy to the leaves of other plants, 

 and their special function is to bear the reproductive 

 organs. The branchlets are elongated processes of 



