120 BOTANICAL MICROTECHNIQUE. 



simultaneous precipitation of the proteids. If no precipi- 

 tation takes place in the sections so treated on the addition 

 of phospho-molybdic acid, while it does occur in the untreated 

 sections, one may deduce the presence of alkaloids in the 

 objects concerned, provided that these were the only sub- 

 stances soluble in tartaric-acid-alcohol which are precipitated 

 l>y phospho-molybdic acid. But this is by no means the 

 case (cf. Molisch, I, 15), and the above reactions can give 

 reliable results only in very special cases. 



The same is true for the other group-reactions for the 

 alkaloids ; but the value of the special reactions for the 

 different alkaloids, to which we now pass, is so much the 

 greater. 



a. Aconitine, C 33 H 43 NO 12 . 



210. According to Errera, Maistriau and Clautriau (I) a 

 solution of iodine and potassium iodide is best adapted for 

 the microchemical recognition of aconitine, with which it 

 forms a red-brown precipitate. These authors also obtained 

 a carmine-red color in presence of aconitine with sulphuric 

 acid diluted with ^ or J of its volume of water, especially 

 after the moistening of the preparations with a solution of 

 cane-sugar. 



b. Atropine, C 17 H 23 NO 3 . 



211. De Wevre (I) used a solution of iodine and iodide of 

 potassium for the microchemical recognition of atropine, in 

 cells containing which a brown precipitate is produced. 

 After some time star-shaped crystallizations with a metallic 

 lustre appeared. Phospho-molybdic acid, which gives a 

 yellow precipitate, is also applicable in many cases. 



c. Berberin, C 20 H 17 NO 4 



212. Berberin occurs, according to the consonant state- 

 ments of Naegeli and Schwendener (I, 503), O. Herrmann 

 (I, 14), and Rosoll (I, 20), in the young cells of Berberis 

 vulgaris as a golden-yellow fluid in the cell-cavity ; while in 



