COLORING AGENTS. 49 



ment with hydrochloric or sulphuric acid removes 

 the color from everything except the bast cells, in 

 which it becomes more intense. 



As a coloring agent in the investigation of pro- 

 tein bodies, this substance has also found use. 1 



CARMINE. 



A solution of carmine in dilute potash, such as 

 is sold by dealers, is used for staining the nuclei of 

 cells. 2 The solution, which should contain very 

 little undissolved carmine, is filtered and then 

 mixed with alcohol or glycerine in various propor- 

 tions. The object requires to lie in the solution 

 for some time. Only the nucleus (and protein 

 grains) imbibe the color. 



The carminate of ammonium (ammonia carmine) 

 is, however, more commonly used. 3 It is prepared 

 in the following manner, suggested by Hartig. 

 Carmine powder is dissolved in a strong solution 

 of ammonia until this is saturated ; the solution 

 is evaporated to dryness over a water bath, and 

 the carminate thus formed is prepared for use by 

 solution in water. 



1 Wigand: Bot. Zeitung, 1862, pp. 129, 139. Maschke: Bot. Zeitung, 

 1859, p. 22. Vogl ; Anat. u. Histol. der unterirdischen Theile von Convol- 

 vulus arvensis. Sitzungsber. d. wiener Akad., 1863, XIII. 



2 Hartig: Der Fiillkern, etc. Karsten's botan. Untersuchungen, I., 

 p. 282, note. 



8 Dippel : Das Mikroskop, I., p. 184. Frey: Mikroskop, 1873, pp. 87, 88, 

 90. Bachmann : Dauerpraparate, p. 26. Tangl : Protoplasma der Erbse. 

 Sitzungsber. der wiener Akad., Bd. XXVI.-XXVIII. 



