PLATE 19 



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1 r f loi 





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t 1 







Crystal-Bearing Fibres of Barks 



1. Frangula (Rhamnus frangula, L.). 



2. Cascara sagrada (Rhamnus purshiana, D.C.). 



3. Spanish licorice (Glycyrrhiza glabra, L.). 



4. Witch-hazel bark (Hamamelis virginiana, L.). 



