520 PRACTICAL BOTANY 



ii. Soluble without evolution of gas in nitric acid. 



iii. Soluble in sulphuric acid, with formation of fresh crystals 

 of calcium sulphate, if only small bulk of fluid be present. 



iv. Are not stained with iodine, &c. 



C. Calcium Carbonate occurs as incrustations (p. 140), or 

 crystals : it is soluble in acetic acid with evolution of bubbles of 

 gas (C0 2 ). 



Protoplasm or Proteids generally. 



i. Coloured yellow or brown by preparations of iodine (pp. 

 26, 27). 



ii. Coloured yellow by nitric acid : on the addition of potash 

 or ammonia a bright yellow colour is produced (xanthoproteic 

 reaction). 



iii. Swells and loses details of structure on treatment with 

 potash, ammonia, or " eau de javelle " (p. 49). 



iv. Stains readily with solutions of carmine, haematoxylin, or 

 Hoffmann's blue ; bright red with Hanstein's aniline violet. 



The best stains for the nucleus, and for showing the details of 

 its structure, are haematoxylin, safranin, and methyl-green. 



Plastids show under favourable circumstances the same re- 

 actions as other proteid bodies. 



Aleurone-grains and crystalloids give also the characteristic 

 reaction of proteids (p. 223). There is a considerable variety in 

 the solubility of these bodies in water, or in salt-solution, in 

 different seeds : the following will serve as types : 



1. Grains without crystalloids. 



a. Soluble in water : peony, almond, cherry, apple. 



b. Partially soluble in water ; more or less readily soluble in 

 10 per cent, solution of common salt. 



a. Soluble in saturated solution of common salt : lupine, 



pea, bean, scarlet-runner. 

 /3. Soluble in saturated solution of common salt only after 



treatment with alcohol : sunflower, turnip, cress. 



2. Grains containing crystalloids. 



a. Partially soluble in water ; more or less readily soluble in 

 10 per cent, solution of common salt. 



a. Soluble in saturated solution of common salt : Brazil 

 nut, pumpkin. 



