I3 2 BOTANICAL MICROTECHNIQUE. 



(Fe 2 (SO 4 ) 3 ) have been added. Most proteids then show, 

 either at once or after some time, a coloration depending not 

 only on the nature of the aldehyde used, but also varying 

 with the different albuminoids, and not appearing at all, with 

 many. The colors with the salicylic and anisic aldehydes 

 and vanillin vary between red, violet, and blue ; while the 

 cinnamic aldehyde produces yellow or orange-yellow colors 

 with proteids. 



Salicylic aldehyde has, according to the statements of the 

 authors mentioned, the advantage of more completely fixing 

 the proteids and of making them more resistent to the dis- 

 solving power of sulphuric acid. 



$. Yellow prussiate and ferric chloride. 



230. Zacharias (I, 211) has lately reintroduced into micro- 

 chemistry a method of recognizing proteids first used by Tru 

 Hartig, which may be here referred to, although it is more 

 a staining process than a chemical reaction. This test was 

 carried out by Zacharias by placing the tissues to be tested 

 for an hour in a mixture of one part of a 10$ aqueous solu- 

 tion of potassium ferrocyanide, one part of water and one 

 part of acetic acid of specific gravity 1.063. This mixture, 

 which must always be freshly prepared, on account of its 

 ready decomposition, is now washed out with 60$ alcohol 

 until the washing fluid no longer gives an acid reaction or a 

 blue color with ferric chloride. Then a dilute solution of 

 ferric chloride is added, which causes a deep blue coloring of 

 the albuminoids (Berlin blue) inconsequence of the ferrocy- 

 anide retained by them. 



231. To recognize albumen in the cytoplasm of Spirogyra* 

 Loew and Bokorny (I) first left the plants an hour in a .\% 

 solution of ammonia, then placed them for 12 hours in a 

 10$ solution of ferrocyanide containing 5$ of acetic acid, then 

 washed in cold water, and finally let them remain for 12 

 hours in a not too dilute solution of ferric chloride. Certain 

 differentiations of the cytoplasm then showed an evident 

 blue color. 



