PLATE XXXVII. 



Fig. 4. Pi-imary vascular bundle, x 375. 



Fig. 5. Section of cross section of old stem, x 100. a, epidermis; b, 

 palisade parenchyma; c, short chloroplast-bearing cells; d, aqueous tissue; 

 e, phloem; /, collenchyma rib. 



Fig. 6. Primary vascular bundle from young stem, x 995. 



Fig. 7. Phloem from primary vascular bundle of old stem. X 450. 

 a, protein gi'ains. 



