Biological Papers. 323 



WINTER CONDITION OF LENTICELS. 



By Leslie A. Kenoyer, Independence. 



ON THE twigs and younger branches of most woody dicotyls 

 there are scattered over the smooth epidermis rough, corky 

 places known as lenticels, A microscopic examination reveals the 

 fact that the tissue just beneath the surface of the lenticel is of a 

 porous nature, the cells being loosely fitted together and separated 

 by large intercellular spaces. Lenticels are developed from stomata, 

 the openings for interchange of gases which occur not only on 

 leaves, but also on young, tender stems. The porous tissue filling 

 the lenticel is produced by the multiplication of cells in either the 

 phellogen or the ground tissue just beneath the stoma. 



The origin and structure of lenticels lead to the belief that they 

 are intended as passages for the circulation of gases. And since 

 they are commonly on parts no longer green, it is generally agreed 

 that their main function is in respiration. The large intercellular 

 spaces found between the corky cells of the lenticel, and often be- 

 tween the cells in the portion of the collenchyma or parenchyma 

 which is just beneath them, admit air to the inner tissues of the 

 plant; and since there are smaller spaces in nearly all the tissues, 

 the cells of the plant individually have access to atmospheric oxy- 

 gen. 



In Gregory's Elements of Plant Anatomy is found the following 

 statement: "At the close of summer, when the time for winter rest 

 draws near, the lenticel is usually closed by the last layers of the 

 phellogen growth; that is, these layers remain a continuous collec- 

 tion of cells and their walls become suberized. In the spring-time 

 the phellogen renews its activity, and the new cells, pushing up as 

 before, break these layers apart and the opening is established 

 anew." 



To ascertain the extent to which lenticels are closed I conducted 

 a series of experiments at the University of Kansas in the fall and 

 winter of 1907-'08. My apparatus consisted of a J-shaped glass 

 tube with the tip of the short arm bent outward from the long 

 arm. The out end of the twig experimented upon was attached to 

 the short arm by means of a short rubber connection, which was 

 wrapped with wire around both the glass tube and the twig to 

 make it air-tight. The short arm and twig were immersed in a 

 vessel of water and mercury was poured into the long arm through 



