78 
WILLIAM H. BROWN 
the water in the cells by some liquid in which their osmotically active 
solutes were insoluble. By thus precipitating these solutes the osmotic 
pressure of the cells would be removed and the leaves might resume 
their original form. Returning such leaves to water should then 
cause them to close again, providing the protoplasmic membranes 
had not been too greatly altered and providing the re-entering water 
might replace the other liquid and again bring the solutes into aqueous 
solution. In such a case the original osmotic pressure would be 
restored to all cells and those of the ventral region should again become 
stretched as at first. To test this possibility a number of leaves 
(some open, some just closed by stimulation, and some closed for a 
half-hour or longer) were killed in boiling water and then passed 
through alcohol to xylene. Since sugars are practically insoluble in 
xylene, the replacement of the water of the cells by this liquid should 
result in a precipitation of sugars, which may be supposed to be of 
prime importance in producing the usual osmotic pressure. The 
leaves killed just after closure reopened in xylene, while those that 
were open and those that had been closed for some time when killed 
showed no alteration. All of the leaves were then returned through 
alcohol to water, which resulted in re-closure of those that had opened 
in xylene, while the others still remained unaltered. In some cases 
such transfers from water to xylene and back again were repeated a 
number of times with the same leaf, and the results were always like 
those just described. As might be expected the distances between 
adjacent ink-dots on the lower surfaces of leaves, showing movement 
decreased when the leaves were changed from water to xylene and 
increased when the reverse transfer was made. The comparative 
measurements from such a transfer of a leaf killed just after closing, 
from water to xylene and back to water, are given in Table VI. 
Table VI 
Comparative Measurements of Distances Between Adjacent Dots on the Lower Surface 
of Dionaea Leaves Killed Just After Closing, as the Leaves were Transferred 
From Water Through Alcohol to Xylene and Back to Water, the Dots 
Arranged in a Line Transverse to the Midrib 
Experiment No. 
L ea n Water 
Leaf in Alcohol 
Leaf in Xylene 
Leaf in Alcohol 
Leaf in Water 
42 
42 
37 
42 
42 
■I--^- 
28 
27 
26 
27 
28 
52 
50 
46 
50 
52 
