PLATE 18 



Fig. 1. Photomicrograi)!! of a portiou of a cioss-scetion of a twig of the 

 current year — viridulits. Stained films in a few cells of the ]iith, absence of 

 rubber in rays and in cortical parenchyma, accumulation of rubber in the bud 

 intrusion. The chloreuchynia is heavily stained. 



Fig. 2. Photograph of a portion of a cross-section of a five-year-old stem — 



I'iriduJus. 



a. The outer limits of the rubber-bearing cortex. 



h. The tangential zone of maximum, cortical, rubber deposition. 



Fig. 3. Photograph of a portiou of a three-year-old shoot — liiidulus. 2s'o 

 rubber in the pith. 



c. The outer limits of the rubbear-bearing cortex. 



Figs. 4 and .">. Photomicrographs showing nature of occinrence of rubber in 

 the cell — gnapJialodes. 



L'<)0 



