DRUGS 341 



poisons when introduced into the animal economy either by the 

 mouth or by hypodermic injection into the circulatory system. 



It is only necessary to mention strychnine, morphine, and 

 atropine, all of which are used in medicine. These and many 

 other substances of the same class have been known for a long 

 time, approaching a century. But beyond the fact that they 

 contain beside carbon, hydrogen, and commonly also oxygen, 

 together with nitrogen, little was known until recent times as to 

 their chemical constitution. They agree in possessing the power 

 of uniting with acids forming definite and usually crystalline 

 salts. This property is connected with the nitrogen they contain, 

 and down to about forty years ago they were assumed to be 

 derivatives of ammonia, and the name alkaloid applied to them 

 all had reference to the basic or alkaline character exhibited 

 more or less strongly by every one. A considerable number of 

 basic substances have been discovered in animal tissues or in pro- 

 ducts of decomposition and in a few cases these are identical 

 with alkaloids derived from vegetable substances. Adenine, for 

 example, is a base of comparatively simple composition with the 

 formula C 5 H 5 N 5 , which occurs not only in the pancreas but in 

 small quantity in tea, beetroot, and shoots of bamboo. Its con- 

 stitution is perfectly well known, not only from a study of its 

 products of decomposition, but from the fact that it has been 

 produced synthetically in the laboratory. 



Another case of a natural alkaloid which has been produced 

 by artificial processes is coniine, the poisonous principle of hem- 

 lock (Conium maculatum). This is a colourless, oily substance, 

 having the formula C 8 H 17 N, which is obtainable from the hem- 

 lock plant or fruits by distillation with a solution of sodium 

 carbonate. It rotates the plane of polarisation to the right. 

 The artificial product is optically inactive as it consists of equal 

 quantities of two stereo-isomeric bases, the one rotating to the 

 right, the other to an equal extent to the left. These were 

 separated from each other by Ladenburg by fractionally crystal- 

 lising the tartrates, and the artificial right-handed base was 

 found to be identical with the natural. 



It will be noticed that the two examples of alkaloids mentioned 

 are devoid of oxygen. When this element is present the problem 

 presented is far more difficult, and, notwithstanding the progress 

 which has actually been accomplished within recent years, as 

 the result of researches by a number of distinguished chemists, 



