DALBEY: SOME SPECIES OP XANTHIUM. 65 



12. The starch sheath is discernible in each species, and 

 contains starch grains and calcium oxalate crystals. 



13. The epidermis of each species contains glucosides in 

 the form of single droplets or of clusters of droplets. 



14. Each species has a ridged cuticle. 



15. Hairs similar to those found on the leaf occur on the 

 stem, numerous in X. globosum and X. americanum, but 

 scanty in X. pennsylvanicum. 



16. Glucosides occur in each species in the phloem, the pa- 

 renchyma, the wood parenchyma and the pith. 



4 — Univ. Sci. Bull., Vol. IX, No. 5. 



