MATERIAL TRANSFORMATIONS IN THE PLANT 1 87 



cane sugar is there any transformation of the latter into starch; Bohm obtained 

 quite analogous results by artificially supplying sugar to the plant. 



§10. Glucosides. 1 — Glucosides 1 are chemical combinations of glucose (some- 

 times of other sugars) with various other substances, and they are split into their 

 component parts by the action of acids or glucoside-splitting enzymes. For 

 example, under the influence of emulsin, arbutin takes up water and produces 

 hydroquinone and glucose. This reaction is shown below:"' 



i O f 



CH 2 OH— CHOH— CH— CHOH— CHOH— CH— OC B H 4 OH (arbutin) + 



- -o 



H 2 (water) = CH 2 OH— CHOH— CH— CHOH— CHOH— CHOH (glucose) + 

 HOCeHjOH (hydroquinone). 



Indican, a glucoside of the indigo plant, etc., forms glucose and indoxyl, 

 with the taking up of water: 



C 7 H 6 NC— O— CeHnOs (indican) + H 2 (water = 



/ C0H \ 

 C6Hi 2 0e (glucose) + C fi H/ ,CH (indoxyl). 



^NH^ 



Indoxyl oxidizes in the air, forming dark blue indigotin (indigo blue) and water: 



2C 8 H 7 ON + 2 = 2 H 2 + Ci 6 H 10 O 2 N 2 . 

 Indigotin has the structural formula, 



/ co \ _ / co \ 



CeHu C — C. .CeH 4 . 



X NH X X NH X 



As a third example may be mentioned amygdalin, an a-$ glucoside of almond, 

 peach, etc., which takes up water and splits into glucose, benzaldehyde and 

 hydrocyanic acid: 



-o- - 



CH 2 OH— CHOH— CH— CHOH— CHOH— CH—0—CH 2 — CHOH— 



C 6H 5 



CH— CHOH— CHOH— CH—O—CH (amvgdalin) + H 2 (water) = 2C 6 H 12 6 



- -o- 



CN 



(glucose) + C 6 H 6 — CHO (benzaldehyde) + HCN (hydrocyanic acid). 



Glucosides may undergo autolysis in the tissues. Thus, if leaves of Polygo- 

 num tinctorium are exposed to an atmosphere saturated with chloroform 

 vapor (which kills the cells), blue indigotin is formed in the tissues. The chlor- 

 ophyll may then be extracted by alcohol, leaving the leaves blue. When 



1 Rijn, van, 1900. [See note 2, p. 333.] 



" This section appears for the first time in the 7th Russian edition. — Ed. 



" For this and similar statements of formulas and reactions, see Haas and Hill, 1913. '[See 

 note 3, p. 6.] Also see works on organic chemistry; an excellent short treatise for physio- 

 logical students is Bernthsen, A., A text-book of organic chemistry. Translated and edited 

 by J- J- Sudborough. New York. 1907. — Ed. 



