1911] OVERTON—TRANSPIRATION AND SAP-FLOW 103 
aqueous solutions of HgCl, CuSO,, and picric acid, Zenker’s 
fixing fluid, KOH, and 4o per cent formalin for o. 5—72 hours. 
In One case 10 cm. of a 40 cm. stem were surrounded for 48 
- hours with picric solution; the involucral leaves drooped in 3 days, 
but were perfectly turgid and did not become discolored and dry for 
26 days, and the branches, which were 10 cm., 11 cm., and 12 cm. 
long, remained fresh for 44 days. The incasing tube was then re- 
moved and the plant was apparently in good condition. The 
stem was obviously dead, the immersed region being discolored, but . 
there was no contraction of the protoplasts observable. Other 
experiments with picric acid are described in table X below. 
In experiments with chromic acid, HgCl., Zenker’s fluid, forma- 
lin, and KOH, the plants very soon faded, although not always 
losing the turgidity of their leaves immediately after treatment. 
By using 95 per cent alcohol and CuSO, I have obtained some 
striking results. On April 12 a plant 35 cm. high, with four 
branches on the crown, was chosen and the stem incased in a glass 
tube; 95 per cent alcohol was poured into the tube so as to immerse 
the stem for 9 cm. The lower portion of the treated region was 
slightly mechanically injured, so that the alcohol could be readily 
absorbed; that it was absorbed was shown by a lowering of the 
fluid in the tube. At the end of 48 hours the leaves of the crown had 
shown signs of drooping and the liquid was removed; after 7 days 
the crown leaves and two branches were partially withered. Six 
of the crown leaves faded and yellowed in ro days, one branch 
showed one leaf, and one branch showed 2 leaves alive for 6 weeks. 
The remaining crown leaves continued green, with but portions 
yellow, and the remaining 2 branches kept on growing, and at this 
writing (July 18), after 76 days, were 6 and 8 cm. long respectively, 
having grown about 5 cm. each. Furthermore, 10 days after treat- 
ment, 7 new branches started, all of which were growing (July 18). 
The incasing tube was removed from the stem, and it was examined 
to be sure a section was dead. As to this there can be no question, 
as is shown by the photograph (fig. 2). Asa result of this examina- 
tion, it was found that 4 cm. of the stem where injured were entirely 
brown and the parenchyma disorganized, which appears black in 
the figure, but apparently no substance had been carried into the 
