APPENDIX. 



DISTRIBUTION OF TANNIN IN TANBARK OAK. 



By C. D. MELL. * 



Tannin is found in most plants and almost exclusively in the living 

 cells, though there are some in whose cells it is not found, such as 

 European hackberry (Celtis australis Linn.), white mulberry (Morus 

 alba Linn.), black elder (Sambucus canadensis Linn.), honey locust 

 (Gleditsia triacanthos Linn.), black locust (Robinia pseudacacia 

 Linn.), and laburnum (Cytisus laburnum Linn.). It is always in 

 the form of a solution in the cells and not in the cell membrane, nor 

 in its primary membrane. Tannin, chlorophyll, and starch are 

 closely associated; tannin and chlorophyll together in collenchyma 

 and phelloderm, and tannin and starch together in the same cells in 

 pith rays. Tannin is most abundant in the elements outside the 

 cambium, and in a few cases it is present sparingly in wood fibers. 



An investigation of the tannin contents of a number of trees shows 

 that several of the elements of tanbark oak have tannin distributed 

 through them, as shown in Table 12. Tannin is present in such of 

 the structural elements of each wood as are indicated by the letter x. 

 The small circle indicates that the tannin content in the element, so 

 marked is very small, and of no importance in connection with 

 commercial operations. 



TABLE 12. Elements of pith, wood, and bark of trees containing tannin. 



Quercus dcnsiflora Hook, and Am. (tan- 

 bark oak) 



Alnus glutinosa (L.) Gaertn. (black alder). 



Betula papyri/era Marsh, (paper birch) 



Carpinus caroliniana Walt, (blue beech)... 



Corylus americana Walt, (hazel) 



Satix purpurea Linn, (purple willow) 



Platanus occidentalis Linn, (sycamore) 



Hamamelis virginiana Linn, (witch hazel). 

 Acer platanoides Linn. (Norway maple) ... 



Rhus cotinuft Linn, (young fustic) 



Pyrus communis Linn, (pear) 



Eucalyptus cordata Labill . (gum ) 



Ribes rubrum Linn, (currant) 



Syringa vulgaris Linn, (lilac) 



Fraxinu* americana Linn, (white ash) 



Structural elements containing tannin. 



x 



\ 



x 



33 



