148 Guayule. 



DESCRIPTION OF PLATE 32. 



i , 6. Sections of resin-canals in which trichome-like structures occurred. 



2. Transverse section through a 20-year-old cortex. 



3. Pith-canal with pseudotylose. 



4. Primary cortical canal of the stem with pseudotylose ; the spread of peri derm 



(pd.) about a stereome bundle is shown. 



5. Pseudotylose in an old cortical canal. 



6. Trichome-like columns formed in pith in seedlings of slow growth. 



7. Primary (endodermal) root canal with pseudotylose. 



