138 Guayule. 



DESCRIPTION OF PLATE 27. 



1. Hypocotyl, irrigated seedling of very rapid growth, about 2 months old. 



2. Wood of irrigated stem 6.5 mm. in diameter. 



3. Wood of field stem 8 mm. in diameter. (Figs. 2 and 3 are drawn to same scale.) 



4. An irrigated stem. 



5. Growth of 1907, terminal twig of a very large field plant. (Figs. 4 and 5 are 



drawn to same scale.) 



6. Irrigated seedling of very slow growth. 



7. Irrigated seedling of very rapid growth. 



8. Field seedling. (Figs. 6 to 8 are drawn to same scale; the total wood to the 



scale shown, libriform to a larger scale.) 



9. Base of growth of 1908, Cedros, irrigated plant, i year's growth. 



10. 2 years' growth (1906-07), field plant, Cedros. (Figs. 9 to 10 are drawn to same 

 scale.) 



