45 



fortunately he gives no definition of vessel and cell ; were this 

 done, it would be possible to show directly, that in this case 

 it is merely a dispute about words, which I have endeavoured 

 to put an end to in my Physiology, i. p. 78, &c. 



M. Biot* has coloured the flowers of white hyacinths red, 

 by absorption of the sap of Phytolacca decandra, an experi- 

 ment performed more than a hundred years ago, and which 

 since then has been frequently repeated by various observers, 

 but not always with success. 



Anatomico-physiological and Chemical Researches on the 

 Colours of Vegetables. 



We have also obtained in the past year very important ad- 

 ditions to the doctrine of the colours of plants. M. Mohlf has 

 especially examined in an anatomical and physiological point of 

 view, the winter colours of those plants which retain their leaves 

 during this period of the year ; he divides these plants, in re- 

 ference to the preservation of their leaves, into several, although 

 not very accurately defined, groups. In one portion of the 

 plants growing wild, or frequently cultivated in the neigh- 

 bourhood of Tubingen, all or most of the leaves developed in 

 summer pass not only through the winter, but also the follow- 

 ing or even several summers. These plants form the first 

 group, to which belong most of the Conifera, Hedera Helix, 

 Iberis sempervirens,Sempervivum, most of the species ofSedum, 

 Empetrum nigrum, Azalea, and all other plants with coriaceous 

 and evergreen leaves. 



A second class of leaves, which remain green during winter, 

 is formed by those biennials, or even perennials, which have 

 rosettes formed from the so-called radicle leaves, which are 

 developed in the course of the preceding summer or autumn 

 in the plants grown from seeds, or from buds which shoot 

 out from the rhizoma. The rosettes retain their freshness 

 during the winter but die off in spring, and this takes place 

 from without inwards ; frequently the inner leaves only par- 

 tially die off. The life of these leaves extends only to the 

 next period of vegetation, and under this group are classed 



* L'Institut, 1837, p. I. 



f Untcrsuchungen uber die wintevliche Farbung der Blatter. An In- 

 augural Dissertation, Tubingen, 1837. 



