.246 



A TEXT-BOOK OF BOTANY. 

 EXAMINATION OF CELL-CONTENTS 



I, 2, and 3 have characteristic appearance (see Frontispiece). 

 4. Crystals of characteristic forms, soluble in hydrochloric acid 

 and insoluble m acetic acid. 5. Crystalline in fresh material 

 treated with alcohol. The glucoses give a reddish precipitate with 

 Fehling's solution. 6. Piperine separates in definite crystals in 

 the plant cell ; the alkaloids of hydrastis form crystallizable salts 

 with sulphuric or nitric acids; the alkaloids in hydrastis, ipecac, 

 coffee, tea, and guarana yield crystalline sublimates. 7. Concen- 

 trated sulphuric acid gives with strophanthin a bright green color. 

 8. Phyto-globulins form definite crystals (see paragraph on 

 aleurone grains). 9. Blue with dilute iodine solution, except the 

 amylo-dextrin starches, as mace, which are colored red. 10. 

 Sphere-crystals in fresh material treated with alcohol, n. Colored 

 blue with alcoholic solutions of methylene blue. 12. Reddish- 

 brown with copper acetate solutions. 13. Terpene resins are 

 colored green with copper acetate solutions. 14. Separation in 

 the form of large globules on the application of sulphuric. acid or 

 solution of hydrated chloral. The volatile oils are more soluble in 

 alcohol than fixed oils, the latter being completely removed from 

 the cells by the use of ether or other similar solvent. 15. Latex 

 occurs as an emulsion consisting of numerous globules. 16. 

 Calcium carbonate dissolves with an effervescence on the addi- 

 tion of hydrochloric acid or acetic acid. 



Factors Influencing 'Growth. Plants have certain inherent 

 or inherited tendencies or characters which make up the inner 

 constitution, and this cannot be modified by external agencies 

 except within more or less narrow limits. Depending upon this 

 character we find plants as different in kind as the apple tree 

 and pine growing under precisely the same conditions. In other 



