THE VENTILATORS OF A ROSE TWIG 



The irregular openings or "eruptive craters" in the bark, photographsd uidar high magnifica- 

 tion, are known as lenticels, and serve as pores through which air is admitted to the inside 

 of the plant. By channels and passages of various kinds between the interior cells of the 

 plant, the air passes to even the most distant parts. The plant is thus enabled to renew 

 its supply of oxygen, and at the same time it discharges carboa dioxids through the lenticels. 

 (Fig. 3.) 



