AXTITOCYAN IX TTTE PETALOID CALYX. / 



but this substance never develops later on into any coloured 

 anthocyan. Xow tbe question arises wliy in certcun flowers 

 protanthocyan precedes a coloured antbocyan wbile in some 

 otbers it does not. Tbe answer is to be sougbt, probably, in tlie 

 bereditary disposition of eacb plnnt. 



Tbat tbe colourless protantbocyan becomes yellow by tbe 

 action of alkalis, as stated in preceding table, is wortb noticing, 

 for it proves tbe presence of a tannin substance, as Wiesner^^ 

 observed. Tbe cbange of tbe colour of yellow anthocyan, wben 

 well developed, to a ligbt red by tbe action of acids, is also of 

 some interest. jNIoreover, tbe existence of intercellular air-spaces 

 and the exceedingly abundant presence of tbe crystals of ciileium 

 oxalate at tbis stase is wortb reraarkins:. 



The Second Phase. 



Duration of observation : July 1 — July 20. External form. — 

 Eacb wbite calyx-leaf of tbe opened flowei's now begins to 

 colour, by tbe appearance of red spots from tbe distal end of 

 its upper side. Tbe colour proceeds along tbe tnargin centripetally 

 over tbe surface (Fig. .^.4). In general, tbis propagation of colour 

 occurs earlier on tbe larger calyx-leaf tbnn on tbe smaller one, 

 tbougb at the end tbe wbole u]3per surface becomes coloured, 

 except tbe borders of tbe veins. For tbis development of colour 

 it is necessary tbat tbe calyx sbould be exposed directly to tbe 

 sunlight, the overlapped part of the upper side of a calyx-leaf 

 and also the wbole lower side being not at all tinged till the 

 end of this phase. 



1) Wiesner, J. — Einige Beobachtungen über Gerb- nn'l Fni-bstoTe der Blnnienbliitter. 

 (Bot. Zeitg, 1862, p. 389). 



