402 BOTANY AND PHARMACOGNOSY. 



40 per cent, of a fixed oil, the seeds contain a peculiar glucosidal 

 tannin, helianthic acid, which is colored deep green with ferric 

 chloride and yellow with alkalies. The root contains inulin; the 

 shoot asparagin, and the fresh pith about 1.5 per cent, of potas- 

 sium nitrate. The latter has been used in the preparation of 

 MoxA, a combustible vegetable material which burns without fus- 

 ing and is used by the Portuguese to destroy any deep-seated 

 inflammation. The pith of various species of Artemisia, which 

 also contains considerable potassium nitrate, furnishes the Chinese 

 Moxa. 



Jerusalem Artichoke (Helianthus tuberosus) is a large, 

 coarse, pubescent herb with yellow ray-florets, which is indigenous 

 to the Middle United States and sometimes cultivated. The 

 tubers, which resemble artichokes, are more or less elongated or 

 pear-shaped, reddish-brown, somewhat annulate, and internally 

 white or reddish. They have been used as a substitute for pota- 

 toes and contain about 16 per cent, of the following carbohydrates : 

 Inulin, pseudo-inulin, inulenin, saccharose, helianthenin, and 

 synantherin. In early spring with the development of the tubers 

 there is formed a small quantity of dextrose and levulose. 



The Globe artichoke of the gardens {Cynara Scolymus) is a 

 hardy perennial and is valued on account of the fleshy involucral 

 scales and torus, which are edible. 



The POLLEN of a number of plants of the Compositae, as rag- 

 weed (Ambrosia), goldenrod (Solidago), aster and chrysanthe- 

 mum, is said to be responsible for the autumnal cold, known as 

 HAY FEVER. A similar disease is produced in spring and early 

 summer by the pollen of certain grasses. It has been found that 

 the pollen grains of these plants contain a highly toxic substance, 

 belonging to the toxalbumins, which is the cause of the disease. 

 By inoculation of rabbits, goats and horses with this toxalbumin 

 a serum containing an antitoxin is obtained which neutralizes the 

 pollen toxin and protects those who are susceptible to hay fever 

 from its attacks. In practice the serum is prepared by injecting 

 the toxalbumin subcutaneously into horses, the serum being known 

 in commerce as pollantin. 



