40 SCIENCE PROGRESS 



but there are a few which are of historical and general interest, 

 and which may, therefore, be referred to more particularly. 

 In 1 73 1 Madden, 1 in a paper communicated to the Royal 

 Society, drew attention to the toxicity of cherry-laurel water 

 (a flavouring agent prepared by macerating broken cherry-laurel 

 leaves in water), with the result that a number of investigations 

 were undertaken to ascertain the nature of the toxic constituent ; 

 and the problem was finally solved by Schrader in 1 803, 2 who 

 showed that cherry-laurel water contained prussic acid, which 

 he had recently proved to be poisonous. 



Another interesting case is that of Cassava {Manihot iitilissimci), 

 widely cultivated throughout the tropics for the sake of its 

 starchy, edible root, from which the tapioca of commerce is 

 prepared. The occurrence of a volatile poisonous product in 

 cassava root was first recorded by Fermin 3 in 1764, and in 1836 

 Henry and Boutron-Charlard 4 identified this poisonous con- 

 stituent as prussic acid ; this observation was subsequently 

 confirmed by Francis 5 in the West Indies, who also showed that 

 the production of prussic acid is not confined, as had previously 

 been supposed, to " bitter " cassava, but also takes place in the 

 " sweet " variety, now referred to M.palmata or M. Aipi. Refer- 

 ence may also be made to Jorissen's 6 discovery of the presence 

 of a cyanogenetic glucoside in embryonic flax plants. 



It is remarkable that the production of prussic acid should 

 have been noted in so many plants which are of economic 

 importance. Cassava, flax, and bitter almonds have already 

 been instanced, and in addition to these may be mentioned 

 the seeds of Taraktogenos Kurzii? which are the source of 

 the chaulmugra oil used as a remedy for leprosy and certain 

 skin diseases ; the seeds of Schleichera trijuga* from which 

 " macassar oil " is prepared ; alder bark, 9 used to some extent 

 in medicine ; the roots of Manihot Glaziovii, the plant yielding 

 the Ceara rubber of commerce 10 ; the seeds, leaves, and flowers 



1 Phil. Trans. 1 731, 37, 84. 



2 Trommsdorfs Journal, 1803. 



3 Mem. Acad. Set. Berlin, 1764. 



4 Mem. Acad. Med. Paris, 1836. 



5 Analyst, 1878, 2, 4. 



6 Ann. Agron. 1885, 10, 468. 



7 Power and Gornall, Journ. Chem. Soc. 1904, 85, 838. 



8 Thiimmel, Archiv. der Pliarm. 1891, 229, 182. 



9 Gerber, ibid. 1828. 



10 Van Romburgh, Ann.jard. bot. Buitenzorg, 1899, 16, 1. 



