MICROCHEMISTR Y. 1 37 



The contents of the cells containing emulsin become red 

 with Milton s reagent, and violet with copper sulphate and 

 caustic potash. It seems probable that these reactions are 

 due to the emulsin, since the corresponding cells of the 

 emulsin-free leaves of Cerasus lusitanica do not give them. 



b. Myrosin. 



241. For the microchemical recognition of myrosin, which 

 is contained in many Cruciferce, Guignard recommends (II) 

 concentrated hydrochloric acid which contains a drop of a 

 iofo aqueous solution of or tin in each ccm. If the sections 

 are heated in this solution to near 100 C, a violet color 

 appears in the cells containing myrosin. 



In the seeds of black mustard and in other parts of various 

 Cruciferce, this reaction occurs in specialized cells rich in 

 proteids, which alone, as Guignard has experimentally shown, 

 are able to decompose potassium myronate (cf. 156). 



[Spatzier (I) finds myrosin also in the Resedacece and in the 

 seeds of the Violacece and Tropaolacece. Where it occurs in 

 vegetative organs he finds it in a dissolved condition ; but 

 in dry seeds it is in the form of solid homogeneous granules 

 of about the size of aleurone grains.] 



