

476 



BOTANICAL GAZETTE 



[JUNE 



occasionally in the layers c and d y but saponification crystals were 

 not obtained in place in the tissue. 



That lipoid substances are present in the peanut membrane 

 is shown by the analysis of the membrane given later in this paper. 

 It is probable that the lipoids are present in a very fine state of 

 dispersion. No distinctly suberized layers could be detected in 

 the seed coat. All protein tests were likewise negative. 



The hot water extraction removes most of the extractable 

 tannins from the membranes, also part of the lipoid materials; 

 the increase in permeability by heating the membrane in boiling 

 water is nrobablv due in larere measure to the removal of these 



meability 



removal of lipoid ma 



terials. 



The high permeability of the peanut membrane as com- 

 pared with other membranes studied is related to its low lipoid 

 content, and especially to the lack of the layers of cells filled with 

 lipoid substances that were found in the other seed coats. 



Membrane of cocklebur (Xanthium pennsylvanicum) 

 The walls at a (fig. 2) are thick and lignified; those at b are 



much 



at c 



is a suberized layer containing tannins. Tannins also appear in b, 



Fig. 2. — Cross-section of seed coat of Xanthium pennsylvanicum, X45° 



but may have diffused there from c . The layer at d and e is an 

 endosperm layer ; the cell walls marked e are composed of cellulose 

 and pectin, and the contents d are of lipoid substances. Extrac- 

 tion with lipoid solvents does not completely remove the fatty 

 substances from this layer. Protein tests all gave negative results. 

 Layers a and c are resistant to chromic acid, but layer d, e breaks up, 

 and the fatty substances flow out in drops. 



