J '28 H. W. KIN<^ ON yilK PHYSIOLOGY OP MONSTRRA DELICIOSA. 



strength to the older roots. The free-growing end of the root, 

 known as the spongiole, develops by the growth of simple 

 spherical cells, which are gradually pressed outwards by others 

 forming, and as they are forced to the exterior they become 

 elongated and form the cylindrical cells, which, in due course, 

 receive the deposit referred to, and become hard and capable of 

 I'esisting great pressure. 



The stem is composed largely of oblong cells of cellular 

 tissue, similar to those found in the root ; they are the first 

 series of the cellular structures connected with the cuticle and 

 rough prominences, then groups of spiral vessels imbedded in 

 woody fibre, and next to these scalariform ducts, along the 

 sides of which run disconnected bands of raphides, individually 

 of a long needle shape, while interspersed in the cellular 

 structure which follows are a number of another kind of 

 raphides, which form clusters of square-shaped crystals, in 

 spaces round which the cellular structure often radiates. 

 Similar forms of raphides frequently occur in the cells them- 

 selves, and it is possible the apparent spaces were formerly 

 cells in which the raphides were formed, and whose cell walls 

 have become ruptured and absorbed, causing a modified 

 arrangement of the cells surrounding them. Pitted ducts, 

 three to four cells broad, pass down by the side of this 

 formation. Both the stem and root are free from laticiferous 

 tissue. 



The upper half of the node may be seen to swell, and 

 gradually the sheath enclosing the leaf bursts through the 

 stem in a similar manner to the bursting of the root from the 

 lower half, developing out from the growing point of the stem 

 about 18 inches, at the sa.me time slowly changing from a 

 cream colour until it acquires a rich green ; then the leaf blade 

 which is developing contiguous to, and in the same perpen- 

 dicular line of growth as the petiole, bursts the sheath sur- 

 rounding it at the free end, and as the leaf blade continues to 

 mature it uncoils, at the same time the sheath splits, and 

 falling, suspended by its base, turns brown, shrivels, and is 

 finally cast off the plant, leaving exposed the cavity in the 

 under side of the petiole that helped to protect the blade- 

 Meanwhile the leaf, continuing its growth rapidly, unfolds the 

 fi^esh verdure of the beautifully perforated and divided lamina, 



