MINERAL ACIDS. 21 



also gave good results. Staining and hardening 

 were thus effected simultaneously, the terminal 

 buds of Chara serving as material for the study. 



PHOSPHORIC ACID. 



This has a limited usefulness through inducing 

 the imbibition of water. It causes crystalloids to 

 swell. 1 [Its occasional use in the cellulose test 

 has already been mentioned cf. p. 5.] 



HYDROCHLORIC ACID (Muriatic Acid). 



Like other powerful acids this 2 induces the 

 swelling of starch, and young cell-walls, especially 

 when it is concentrated. Its employment in Han- 

 stein's method of clearing tissues has been already 

 mentioned (cf. p. 11). Kabsch 3 has used it with 

 concentrated sulphuric acid and potash to isolate 

 the tertiary lamella of wood-cells, the sections be- 

 ing successively treated with the separate reagents, 

 and washed with water after each has acted a suf- 

 ficient length of time. 



After lying in the acid for a long time nitrogen- 

 ous substances (protein matters) assume a violet 



1 Hofmeister: Handbuch, I., several places. Kraus: Jahrb. wiss. 

 Bot., VIII., Crystalloids in the Epidermis. 



2 Dippel : Das Mikroskop, I., p. 276 ; II., p. 41. Hohnel : Sitzber. 

 wien. Akad., 1877, Abth., I., p. 21. 



3 Jahrb. wiss. Bot., 1863, III. 



