The Structure of the Cork Tissues in Roots 

 of Some Rosaceous Genera. 



{WITH PLATE X) 



By Martha Bunting, Ph. D. 



IN his paper upon " Plant Hybrids "* Professor J. M. Macfar- 

 lane noted the presence of intercellular spaces in the cork 

 region of the roots of Getan tirbarium and G. rivalc. While I 

 was studying at the University of Pennsylvania during the sum- 

 mer of 1895, he suggested that I should try to ascertain whether 

 the existence of intercellular spaces in the cork region was a 

 definite character of the roots of Rosaceous genera. Since 

 the summer of 1895 the study has been continued at intervals 

 at the University of Pennsylvania and at the Woman's College 

 of Baltimore. I wish to extend my thanks to Professor 

 Macfarlane for his ever ready assistance and criticism of the 

 work, as well as his very generous supply of material from the 

 Botanical Garden of the University. 



In addition to the paper already noted, I have found refer- 

 ence to intercellular spaces, in the cork region of Rosaceous 

 genera, only in the following quotation taken from Vines' 

 text-book of Botany, published in 1895 : "The cells of the 

 periderm are not always completely suberized. In some cases 

 (roots and stems of Onagracecc, Hypericacece, some RosacecB, 

 etc.) some layers of the periderm consist of cells with a 

 suberized zone like that of the cells of the endodermis, though 

 these cells usually become completely suberized eventually. 

 In other cases [c. g., stem o{ Poterhun, Alcheinilla, Agrimonia, 

 EpilobiiiDi) the periderm consists mainly of cells with cellulose 



* Trans. Roy. Soc, Edin., Vol. xxxvii, 1892. 



54 



