MINERAL ACIDS. I/ 



comes in contact with. Starch is thus converted 

 into dextrin. 



The cuticularized parts of the cell-wall (cork, 

 cuticle, 1 extine of pollen, exospore, root-cap, etc.) 

 resist the action of this reagent, as does the pre- 

 viously mentioned middle lamella. Protoplasm is 

 destroyed after a time, while young protoplasmic 

 bodies are often colored rose-red under its action, 2 

 the reaction being rendered more certain by the 

 addition of a solution of cane-sugar. Fat-bodies 

 occurring in the protoplasm are not dissolved, but 

 run together, forming small refractive drops. Oil 

 which previously existed, diffused through the pro- 

 toplasmic mass, manifests itself similarly. 3 



NITRIC ACID (Aqua fortis). 



This is employed as a macerating reagent in 

 combination with potassium chlorate, 4 q. v. 



When the contents of a cell are treated with 

 nitric acid alone, or with this reagent followed by 

 ammonia, they assume a bright yellow color when 

 protein matters are present, through the formation 

 of xantho-protein acid. 



According to Hb'hnel, nitric acid, either alone or 



1 DeBary: Hofmeister's Handbuch, III., -1878, pp. 84, 131. Bron- 

 gniart : Ann. Sci. Nat., 1830, i Ser., T. XXL, p. 427. 



2 Sachs: Bot. Zeitung, 1862, p. 242. 



3 Sachs: Bot. Zeitung, 1862, p. 146. 



4 Dippel: Das Mikroskop, I., p. 275. Nageli: Das Mikroskop, 1877, 

 p. 474. Sanio : Bot. Zeit., 1863, p. 362, note. 



