o 



16 SUMMARY OF CURRENT RESEARCHES RELATING TO 



petaloid calyx of Hydrangea Hortensia var. japonica, which was especially 

 suitable because of the slowness with which anthocyan passes through 

 its different phases of development in this plant, and also because of 

 the long duration of its blossoming period. The different phases are as 

 follows : 



Colourless protanthocyan 



Yellow anthocyan 



/ \ 



Reddish anthocyan Bluish anthocyan 

 Deep red anthocyan Deep blue anthocyan 



\ / 



\ iolet anthocyan in crystals 



When the flowers open the petaloid calyx is yellowish or slightly 

 greenish, the colour being due not to chlorophyll but to the cell-sap. 

 At this stage protanthocyan is already formed, and at a later stage passes 

 into yellow anthocyan which colours the sap of the epidermal cells. 

 Chemical reactions indicate that protanthocyan and yellow anthocyan 

 are allied compounds of tannin or modified phenol compounds. In the 

 second phase (July 1-20) the sepals of the open flowers became coloured 

 red, when exposed to sunlight, by development of red anthocyan, the 

 colour spreading from the apex towards the base. Acids do not produce 

 any marked change in the colour of red anthocyan, but alkalis turn it 

 green. In the third phase (July 20 to August 1) most of the flowers 

 tend to nutate, each sepal becoming turned upside down, when the 

 lower side turns red from the base towards the periphery. The colour 

 is less bright than on the upper face. Microscopical examination shows 

 an increasing number of red epidermal cells on the upper face, while 

 some bluish cells are often met with in the hypodermal layer. On the 

 lower face the red cells occur mainly as irregular idioblasts in the hypo- 

 derm. Chlorophyll grains begin to appear at first in the hypodermal 

 cells on both aspects of the leaf, extending later to the middle of the 

 mesophyll. In the last phase (August 1 to September 1) erect flowers 

 can no longer be found. The red colour of the lower face of the sepals 

 becomes darker, chiefly clue to the mixing of the epidermal deep red and 

 the hypodermal blue anthocyan. In this phase microscopic examination 

 reveals violet or bluish crystals in the outer layers of the leaf on both 

 faces. Their chemical reactions agree with those of the blue or violet 

 cell-sap, and they must, therefore, be regarded as anthocyan crystals. 

 They dissolve in acids to form a red solution, in potash to form a pale 

 green solution, and in chloral hydrate without any special change of 

 colour. They are doubtless identical with Zimmermann's "pigment 

 secretion " and Kroemer's violet chromatophore. A refractive globule 

 is found in each epidermal cell in this last phase, which closely resembles 

 those described by Kroemer in the coffee-berry ; it is probably a proteid 

 combined with fatty bodies. 



Farmer, J. B. — On the interpretation of the Quadripolar Spindle in the Hepaticae. 



Bot. Gazette, xxxvii. (1904) pp. 63-5. 



