BITTER SECRETION*. 71 



ifioiij^h by certain intermediate substances they may be 

 rendered capable of uniting with both. 



The Bitter secretion of many plants does not seem 

 ©xactly to accord with any oi the foregoing. Some 

 facts would seem to prove it of a resinous nature, but it 

 is often perfectly soluble in water. Remarkable instan- 

 ces of this secretion are in the Cinchona officinalis or 

 Peruvian bark, Lambert Cinchona^ t. 1, and every spe- 

 cies, more or less, of Gentian. (8) 



Acid secretions are well known to be very general in 

 plants. Formerly one uniform vegetable or acetous 

 acid was supposed common to all plants ; but the refine- 

 ments of modern chemistry have detected in some a 

 peculiar kind, as the Oxalic acid, obtained from Oxalis 

 or Wood Sorrel, and several others. The astringent 

 principle should seem to be a sort of acid, of which 

 there are many different forms or kinds, afld among 

 them the tanning principle of the Oak, Willow, &c.(9) 



(8) [The Gendana saponaria and Gentiana Crinita are two 

 of our most beautiful autumnal plants. The root of the first is 

 •decidedly bitter. 



The roots of Goldthread ( Hdleborus trifolius), of Hydras- 

 tis Canadensis., and Zanthorhiza Jfiiifolia contain the bitter prin- 

 ciple in great abundance. See Professor Barton's Materia 

 Medica of the United StatesJ] 



(9} [Among the North-American Oaks, most esteemed for 

 tpanning, are the Quercus alba, or White Oak, the Quercus vir- 

 ens, or Live Oak of the southern states, Quercus tinctoria, oP 

 Black Oak, Quercua falcata, or Spanish Oak, and Quercus pri- 

 mus monticolay or Rock Cnesnut Oak. For the investigation of 

 this important genus, as well as for their other lanours, we are 



