484 BOTANICAL GAZETTE [june 



5. Extraction with hot water did not measurably increase 

 the permeability of the grapefruit and squash seed coats; but 

 these membranes before such treatment were so resistant to the 

 passage of water that an increase could have resulted from the hot 

 water extraction without being detected by the apparatus under 

 the conditions of the experiment. 



6. Extraction with hot lipoid solvents increased the per- 

 meability of all membranes studied except the seed coat of the 



* 



grapefruit. The percentage of increase ranged from 15 to 871 

 per cent. 



7. Extraction with acetone at room temperature also increased 

 the permeability of all the seed coats except that of the grape- 

 fruit. The percentage increase ranged from 53 to 313 per cent. 



8. After a membrane had its lipoid content removed, its per- 

 meability was decreased by impregnating it with the lipoid material 

 that had been extracted; but in no case was the permeability 

 reduced to the low point exhibited by it before the process of 

 extraction. 



9. Calcium chloride treatments increased the permeability of 

 the membranes, but the cause of this increase could not be deter- 

 mined. 



10. The substances found to be factors in determining the 

 permeability of the membranes to water were lipoids, tannins, 

 and pec tic substances. Suberized layers were not found to be 

 significant in the membranes studied, and the presence of soluble 

 proteins could not be detected. 



I wish to express my thanks to Dr. William Crocker and to 

 Dr. S. H. Eckerson for helpful advice and suggestions during the 

 progress of this work. 



142 South Anderson Street 



Los Angeles, Cal. 



