CVPULIFEBJE. 363 



According to Dr. Stockman, tannic acid exerts no action upon 

 tlie urinary excretion^ and gallic acid does not cause contraction 

 of tlie blood-vesselsj but on the contrary dilates them even 

 after contraction has been induced hj the action of an alkaline 

 liquid. The neutral gallate of soda, in which form gallic acid 

 circulates in the blood, was found to have no action upon the 

 vessels. 



Catechu-tannic acid and Hhatania-tannic acid gave the same 

 results; tannic acid being insoluble in a solution of chloride of 

 sodium could not be experimented with in this manner. Alka- 

 line tannates and tannates of albumin did not affect the calibre 

 of the vessels. Fikentscher has stated that tannic acid adminis- 

 tered hypodermically to frogs stimulates the vaso-motar centres 

 and increases the blood pressure, but Dr. Stockman found that 

 gallate andtannate of soda administered in this way to rabbits did 

 not affect the pressure, Pyrogallic acid yielded similar results. 



As regards the therapeutic value of gallic acid as a local appli- 

 cation or when absorbed into the blood, Dr. Stockman considers 

 that it has no si3ecial astringent action, but that it diminishes 

 the alkalinity of the blood and increases its tendency to 

 coagulate : as a local application it is useless. Tannic acid preci- 

 pitates albumin and forms a protective layer of tannate, which is 

 advantageous in certain diseased conditions which we haA'e 

 already noticed. In its passage through the kidneys it is very 

 doubtful whether it exerts any therapeutic action, but Ribbert 

 considirs that it lessens the exudation of albumin in albumi- 

 nuria. Tannic acid is sometimes injected into the rectum to 



destroy thread worms, which it does by coagulating the albumin 

 in their delicate tissues. 



Description. — Two kinds of gall are found upon Oak 



trees, hard and soft ; the former are the galls of commerce, and 

 are produced by a Cynips which punctures the buds of the tree 

 and deposits its egg in the puncture ; the latter result from 

 the puncture of an aphis. 



Gall-nuts are globular or pyriform bodies, studded with 

 numerous tuberosities; those which still contain the insect are 



