58 BOTANICAL GAZETTE [JANUARY 
ditions were identical with the exception of the use of the decoction 
in making up the nutrient solution. 
Sections were made of the leaves from a stem killed as just 
described. The protoplasts of the mesophyll cells were much 
contracted and the chloroplasts were discolored. The same thing 
is true of the leaves on a stem which has stood for some time in a 
sterilized stem decoction. The leaves from plants grown in a stem 
decoction also show similar appearances. All of my observations 
go to show that the plant after steaming is poisoned. DIxoNn (10) 
finds that discoloration of the leaves above the killed portion, 
and even on a separate branch if its water supply must pass through 
such a heated region, may occur. This he thinks is due to a poison, 
since leaves which wither simply from lack of water shrivel while 
they are still green. In Cyperus I have observed no such marked 
discoloration of leaves before shriveling.* In many cases the leaves 
on a steamed stem dry without any discoloration whatever, 
although the protoplasts of the mesophyll may be completely 
plasmolyzed long before shriveling occurs. In other cases the 
leaves become discolored. ‘ 
UrsprunG believes that experiments with cut branches are 
untrustworthy in such problems as the one under consideration, 
since the conditions are not the same as when the plant is in con- 
nection with the roots. I have made a series of experiments t0 
compare the results with cut branches with those obtained from 
rooted plants. The average daily rate of water loss was obtained 
for each stem, and then a portion of the stem killed with steam OF 
hot wax and the weighings continued. That these cut stems_ 
behave like those in connection with the roots the following results 
will show. A section 10 cm. long of one of two similar cut stems, 
each of which gave off approximately 7 gm. of water in 24 hous, _ 
was steamed for 30 minutes; during the next 24 hours this amount - 
decreased to 3.2 gm., and to 0.5 gm. in the third period, and the 
leaves were very dry. A control plant transpired 5.2 gm. during - 
the first 24 hours, 4.7 gm. during the second 24 hours, and ae 
gm. during the third period. We see that in cut plants there 
the same immediate and continued falling off in transpiration 
after steaming the stem as occurs when the stem is similarly treate¢ 
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