VOLUME LXVI NUMBER 2 
THE 
HOTANICAL “GAZE BEE 
AUGUST 1978 
DETERMINATION OF WILTING 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 241 
ARTHUR L. BAKKE 
(WITH FIVE FIGURES) 
The status of the question of permanent wilting in plants, as 
described by Briccs and SHANTz (5, 6, 7, 8), CALDWELL (11), 
SHIVE and Livineston (37), and Atway (1), centers about the 
determination made by Briccs and SHANrz that a plant is re- 
garded as having attained a condition of permanent wilting when 
it does not recover its turgidity in a period of 24 hours when sur- 
rounded by air saturated with water vapor. The method of 
employing standardized hygrometric paper (2, 3) 4, 28, 30, 38, 40, 
42) in the measurement of the transpiring power in plants consists 
_ in ascertaining the power of a leaf to give off water and comparing 
this with the power represented by a saturated blotting paper sur- 
face at the same time. This is then a measure in both cases of the 
resistance to the passage of water. The conditions which affect 
such measurements are internal, but these internal factors are 
dependent upon external factors. It is obvious, therefore, that 
data derived will be more or less of a resultant complex of all the 
forces which have been operative during the history of the plant. 
The method in principle is the same as has previously been 
used in investigations upon the foliar transpiring power of plants. 
In the present studies filter paper circles (Munktell’s Swedish 
81 
