1915] 
HARVEY—ETHYLENE 
209 
of osmotic pressure under such conditions have apparently been 
made. 
Results with K NO, and glycerine indicate probably two things: 
first, that neither the treated nor the untreated tissues are very 
TABLE IX 
OSMOTIC PRESSURE AND PERMEABILITY 
° Difference in gm.- 
= ‘ ae 
Plasmolyzing Concentration Dainitin oe . mol. between 
t gm.-mol. heparan treated and 
ee atmospheres untreated 
Sucrose 0.37 Roc ge. EAC Ge, Giese ae eg ae 
Glucose vary paces Bg ERIE pages ep Mein Pes eiunee ae 
Untreated. ....... KNO EE ei cw ies ela aes ers a 
Glycerine CS AOE Ge ae Fede ies 
Sucrose 0.46 II.70-11.84 0.09 
Glucose WF Oa eae hea ey 0.10 
wie beagle gycve. K WOO 1 Pay wi vane eee 0.08 
Glycerine OBO re aries aes G.t3 
permeable; and, secondly, that the treated tissue is slightly more 
permeable than the control. 
D. RESPIRATORY CHANGES 
For the study of respiration, the cultural methods differed in 
some respects from those already described. When the epicotyls 
had become 2-3 cm. long (that is, ready for the usual 72 hours’ 
exposure period), the entire seedlings or the epicotyls only were 
taken from the pans and placed in test tubes of 20 cc. capacity, 
graduated for 15 cc. The condition in the test tubes were as fol- 
lows: They were filled with mercury and inverted over a dish of the 
same. The mercury in the tubes was displaced to the 15 cc. mark, 
either with pure air or an ethylene-air mixture containing 0.0002 
per cent ethylene. Three entire seedlings or four epicotyls were 
introduced from below into the various tubes. The experimental 
periods were 3, 6, 12, 24, 48, and 72 hours. At the close of a period 
the seedling or epicotyls were withdrawn by means of a hooked 
wire and the gas present preserved for analysis. The BONNIER 
and MANcIN apparatus was employed for the gas analysis, fol- 
lowing practically the procedure suggested by THopay (32). 
