Demonstration of Alkaloids in Solanaceous Meristems

Abstract

A GENERAL concensus of opinion among investigators has agreed that Boachardat's reagent is the most reliable among many tried for the cytochemical demonstration of alkaloids. It is a general alkaloid reagent, with no specificity, and consists of 1 per cent iodine dissolved in 1 per cent potassium iodide. It colours proteins very heavily. With practice, the red tint and fine grain of the alkaloid precipitate can be readily distinguished from the flocculent brown of the protein. Errera¹ devised the further expedient of treating parallel preparations with a 5 per cent solution of tartaric acid in alcohol. This dissolves out the alkaloids so that a clear distinction should be apparent in alkaloid-containing tissues with and without such pre-treatment. No difference will be apparent if the iodine precipitation is due to protein.