132 Guayule. 



Description of Plate 24. 



1. Cotyledon en face, to show distribution of vascular strands. 

 2-5. Sections through cotyledonary collar and upper part of hypocotyl in an 

 ascending series. 



6. Section through cotyledonary collar, and lower part of first internode. 



7. Section through first node of epicotyl. 



8. Section through stem near second node of epicotyl. 



9-1 1. Section through different levels to show primitive trachea and its relations 

 to older elements. 



9. Base of hypocotyl. 



10. Middle of hypocotyl. 



11. Base of cotyledonary collar. 



12. Origin of cauline strands at a level between those of figs. 4 and 5, but in a 



younger specimen. 



13. Diagram of the vascular tissue (hadrome) in the plantlet. Arrows indicate 



fusion; dotted line the primary trachea. 



