472 



BOTANICAL GAZETTE 



[JUNE 



show large differences, but in general acetone and ether were 

 more effective than alcohol in increasing the rate, possibly due to 

 their better dissolving power. The effect of the lipoid solvents 

 upon the permeability of the squash membrane is to be noted 

 especially. Most squash membranes will not show any penetra- 

 tion by water under the conditions of these experiments until they 

 are treated with a lipoid solvent. They then become rather perme- 

 able to water. 



Effect of extracting membranes with cold lipoid solvent 



The significance of lipoids in the membranes is well shown by the 

 series of measurements made when the extraction was carried on at 

 room temperature. The unheated membranes were merely placed 

 in bottles of acetone and allowed to undergo extraction at room 

 temperature for 18 hours. The permeability of the membranes 

 was measured before and after such treatment. Table IV shows 

 the results of this experiment. 



TABLE IV 



Effect of extracting membranes with cold lipoid solvent 



Membrane 



Peanut. . . 



u 



u 

 Pumpkin. . 



u 



Squash . . . 



u 



Almond . . . 



a. 



Grapefruit 



Area in sq 

 mm. 



5 -265 

 I9-63S 



50- 265 

 u 



I9-635 



50-26S 

 19-635 



Concen- 

 tration of 

 solution 



Rate before 

 extraction 



0.5 M 



u 

 u 

 a 



Saturated 



u 



u 

 a 

 « 

 a 



14 

 65 

 36 

 24 



O 



4 

 o 



49 



00 



27 



04 



1752 

 101 . 10 



Rate after ex- 

 traction with 

 cold acetone 



60.66 



246 . 68 



88.29 



76.84 

 251.77 

 141.54 

 118.64 



107.84 



34-37 



153-67 

 o 



Percentage of 

 increase 



318.6 



275.4 



145-3 

 216.6 



96.18 

 53-21 



Infiltration experiments 



Experiments were made to infiltrate the extracted membrane 

 with the extracted material. Membranes that had been extracted 

 were soaked in the solvent containing the lipoid extract and then 

 exposed to evaporation; by a continuance of this process it was 

 hoped to impregnate the membrane again with the material that 



