C. A. BARBER 



157 



ill length of the internodes to which they are attached. In the young shoot 

 each leaf sheath is entirely covered by the one outside it, while it is yet un- 

 developed, but the moment when it emerges from this protection Kamerling 

 shows to coincide with its cessation of growth. The tops of two successive 

 sheaths are now close together, and any further separation is due to extension 

 of th3 stem which at this period commences to elongate. The top of 

 the leaf sheath is the place where it joins the lamina, and Kamerling selected 

 this point which Ife calls the " blad-gewricht " (leaf joint), as the one by the 

 observation of which he could indirectly observe the growth in length of 



young joints of the stem apex {see Fig. above). This demonstration of 

 Kamerling's has been found to be justified, on the assumption that all of the 

 mature leaf sheaths are of equal length. He measured a series of leaf sheaths in 

 different canes and soon found that, while the difEerences in their length in fully 

 grown parts of the cane plant were very small, both at the beginning and end of 

 the vegetative season the leaf sheaths were of different sizes. The first sheaths 

 are very small, these successively increase in length until they reach a fairly 



