(85) 



bulbils, or rather by which bulbils instead of branches are 

 formed, seems to consist in a stoppage of the development of 

 the stelar tissues and an exaggerated production of the cortex. 

 This action makes the bulbils very similar to the rhizomes in 

 general anatomy, and as may be seen later the bulbils actu- 

 ally pass into rhizomes when they continue their growth in 

 the soil. The central pith has about the same bulk as that of 

 the aerial stems ; the elements as well as those of the cortex are 

 globose and furnished with large intercellular spaces. The 

 protoxylem consists of a number of elongated elements of the 

 customary type, and the protophloem is a thin ring of cambi- 

 form cells and companion cells, with a fairly well-marked 

 sheath marking the inner boundary of the cortex. The cor- 

 tical cells are arranged in radial plates after the manner 



Fig. 5. Germinating bulbil, showing origin <>i roots. X 4- 

 of aquatic stems. An outer region of live or six layers has 

 the elements more compactly arranged; these contain stan li 

 and chlorophyl in abundance, and many <•! them in common 

 with the epidermis include red coloring matter, and agran- 

 ular substance the identity of which has not been ascertained. 



