414 STARCHES, GLANDS, &c. 



Varieties. White galls are the galls collected after the escape of the 

 gall-wasp ; they are rather larger than the ' blue ' galls, rather lighter 

 in weight, and yellowish in colour. They are less esteemed, and are 

 considered to contain less gallotannic acid, which, however, does not 

 from analyses appear always to be the case. 



Chinese and Japanese galls are produced by Aphis chinensis, Bell., 

 on Ehus semidlata, Murray (N.O. Anacardidcece) ; they are of a very 

 irregularly lobed shape, reddish brown in colour, hollow and covered 

 with a thick, grey, velvety down. They are largely used in the manu- 

 facture of gallotannic acid, of which they contain about 70 per cent. 



COWHAGE 



(Mucuna) 



Source, &C. Cowhage consists of the hairs attached to the fruit 

 of Mucuna pruriens, de Candolle (N.O. Leguminosce) , a climbing plant 

 indigenous to India, Africa, and South America. 



The fruit, a small, curved, nearly black legume, is densely covered 

 with stiff yellowish brown hairs which form the commercial drug. 



Description. Cowhage appears in commerce as a yellowish brown, 

 loosely felted mass of hairs with occasional small black portions of the 

 pericarp. Examined under the microscope it is seen to consist of one- 

 celled, thin-walled, sharply pointed hairs which are 2 or 3 mm. long, 

 and bear numerous short, often recurved prominences. 



Constituents and Uses. The hairs contain a little tannin, but their 

 action as a vermifuge is purely mechanical. 



