222 THE JOURNAL OF INDIAN BOTANY. 



distension of the stalk whereas the one in Crone's solution responded 

 to the medium and appeared with bladders of the intermediate type 

 already shown above. It was also noticed that the absorption of 

 water from the dilute solution was so enormous that after a warm 

 day when the Temperature suddenly cooled down from 86°F at 3 P.M, 

 to 76°F at 5 P.M. there was copious exudation of water from the apex 

 which was not the case in the other two plants. It may, in this con- 

 noction, be pointed out that the function of the apical gland appears 

 to be rather to serve as a hydathode than as an absorbing organ as 

 maintained by Goebel (2). 



Anatomy: — As an effect of this high-water content notable 

 changes are brought about in the growth of the leaf stalk. The 

 turgidity of the cells is maintained by a high hydrostatic pressure 

 which leads to the dilution of the cell sap as evidenced by the fact 

 that - the cells plasmolyse readily with a 1/5 normal solution of 

 potassium nitrate, whereas this concentration is only just enough to 

 overcome the rigidity of the cells in the long stalked leaf. The living 

 cells of the leaf stalk thus become so much gorged with water that 

 a plastic stretching of the cell walls ensues due to superficial 

 growth, and as the cells of both transverse and vertical layers are 

 subjected to this process the stalk assumes a spherical distension 

 comparable to an inflated bladdcler, and is filled with numerous poly- 

 hedral chambers bounded by layers of thin-walled cells (diaphragms) 

 in an extremely stretched condition. Owing to this plastic stretching 

 from the beginning the intercellular spaces in the diaphragm are 

 considerably reduced and are practically confined to the periphery. 

 Against this may be contrasted the structure of the bladderless stalk. 

 This shows numerous air cavities which are partitioned by diaphragms 

 but these are pierced by intercellular spaces from the earliest stage 

 which points to the absence of any stretching due to turgidity. The 

 intercellular spaces arise by the separation from each other of the 

 walls of the diaphragms cells at several points and the air cavities 

 communicating in this way evidently facilitate rapid diffusion of gas 

 from the aerial organs to the root-system which is badly aerated, being 

 fixed in mud or under other conditions referred to below. In the 

 bladdered leaves, however, the diffusion of air contained in the 

 chambers must be a slow process occurring only through the cell walls 

 as the cavities do not communicate with each other. The presence 

 of needle shaped crystals of calcium oxalate in considerable amounts 

 also suggests the previous formation of oxalic acid which probably 

 maintains a high osmotic pressure owing to the peculiar conditions 

 which lead to the diminished water content. The principal changes 

 in the anatomy are shown below : — 



