228 BOHDAN SLAViK 



mation was carried out at 25 °C. It was ascertained before the experiment 

 that different size of the discs and thus a different ratio of the total intact 

 area to the cut plane area had but a neghgible effect on the relative 

 values of respiratory intensity. These values are expressed in /xl. COg/mg. 

 dry weight/hr. 



Parallel material was used for determining the number and size of 

 stomata by direct microscopy. The density of stomata was expressed as 

 number per i mm^ leaf area, the size as the length of the pore in /n. Under 

 the theoretical assumption that the stomata are of the same shape all over 

 the leaf-blade, i.e. that the index of length to maximum width of the 

 pore is the same, the pore area is proportional to the square of its length. 

 The product of the density and square of pore length (together with the 

 sum of these values for the lower and upper part of the leaf-blade) is 

 given as the relative index of the area of pores. 



I am indebted to Mrs. Krejcarova for her skilled technical assistance. 



RESULTS 



Gradients of the osmotic pressure of the cell sap of a single material were the 

 following: during average osmotic pressure of the cell sap in the leaf-blade 

 apex amounting to 12-9+ 0-3 atm. the average osmotic pressure at the 

 base was io-6±o-32 atm, i.e. lower by 18 per cent. The difference of 2-3 

 ± 0-20 atm is very significant statistically (see Table i). 



Table i 

 Review of results 



OP PR R ST 



, < 



Leaf-blade apex I2-9 + 0-3 io-8±i-3 2-4±0'o6 135-0 



Leaf-blade base io-6±o-3 i2'9+i-2 2-7±o-07 139-3 



OP — osmotic pressure in atm. 



PR — phosynthetic rate in nig. COg per dm^ per hour. 



R — rate of respiration Qo, in fxl. COg per dry weight per hour. 



ST — relative index of total pore area (see text and Table 2). 



