ANTHOCYAN IN THE PETALOID CALYX. 17 



The presence of sugar in the calyx-leaf of Hortense is observed 

 only in the earlier phases of its development. Sugar may have 

 no close connection with the formation of anthocyan. 



d). Mechanical injury. — Mechanical stimuli hasten the forma- 

 tion of red anthocyan from protanthocyan. When the calyx 

 surface is scratched with a nail, the injured part in a few days 

 becomes much more intensely red than the healthy part. (Fig. 9.). 

 This test is effective only in the later stages of the growth ofl^ 

 the calyx-leaf. It is already known that any diseased or injured 

 part of leaves or fruit may easily develope red anthocyan, and 

 Molisch^^ has recently observed a sudden development of a carmin 

 red pigment on making a nail-scratch on the surflice of a leaf 

 of Schenckia blumenaviana. Ludwig and Linsbauer'-' also noticed 

 the formation of coloured anthocyan under the influence of 

 mechanical injury. 



e). Soil. — The formation of anthocyan in the calyx of 

 Hortense is probably more or less influenced by the nature of 

 the soil. Schübler,"' Darwin,^' Molish,^' Miyoshi'^' and others all . 

 ascertained that the colours of the anthocyan of Hydrangea-flowers 

 are much influenced by the chemical nature of the soil. Darwin 

 observed that alum directly influences the colour of Hydrangea- 



1) Molisch, H. — Ueber ein neues, einen carminrotlien Farbstofl" erzeugendes Chromogen 

 bei f:;chenckia blumenaviana, K. Seh. (Ber. Deutsch. Bot. Ges. Bd. XIX. Heft 3). 



2) Linsbauer, Ludwig. — Einige Bemerkungen über Anthocyanbiklung. (Oesterreichisclie 

 Bot. Zeitg. Jahrg. LI. 1901). 



3) Schübler.— Untersuchung einer Erde welche die Eigenschaft Jiatte, die gewöhnlich 

 rothblühende Hortensia speciosa blau zu färben. (Schweigger's und Meineke'a Jahrb. d. 

 Chem. u. Physik, 1821). 



4) Darwin, C— The variation of animals and plants under domestication. Vol. II. p. 

 267. (from the Journal of Hort. Soc, Vol. i, p. 160). 



5) Molisch H.— Der Einfluss des Bodens auf die Blüthenfarl)e der Hortensien. (Bot. 

 Zeitg. 1897. p. 58). 



6) Miyoshi, M.— Ueber künstliche Aenderung der Blüthcnfarben. (Bot. Cent. Blatt. Bd. 

 LXXXIII. No. 11. p. 345). 



