50 SCIENCE PROGRESS 



prussic acid begins to appear as soon as the embryo germinates, 

 implying that the amygdalin contained in the seeds is used as 

 a reserve material. Soave deduces from his observations the 

 conclusion that cyanogen compounds are transitional substances 

 furnishing the plant with nitrogenous food. In support of such 

 a view one may urge from the chemical side that the cyanogen 

 group is a highly reactive one, and in particular when suitably 

 combined is readily convertible by simple reactions into amino- 

 derivatives of the type now known to form the nucleus of some 

 of the more simple proteids, and this is probably one of the 

 principal facts which has led Gautier 1 and others to assign a 

 preponderating place to cyanogen and its derivatives in the 

 synthesis of proteids in plants. 



An important point upon which practically nothing is known 

 at present is the method by which prussic acid is first produced 

 in plants, though Gautier has suggested that it may be formed 

 by the reduction of nitrates by formaldehyde. In this connec- 

 tion Treub has observed that, although nitrates are usually 

 almost entirely absent from the laminae of the leaves of 

 Phaseolus lunatus, there is always a supply of these salts in 

 the petiole, which seems to act as a storehouse for this material. 



1 Lemons de chim. biol. Paris : Masson et Cie. 1897. 



