1864. | Botany and Vegetable Physiology. 319 
bore ninety-one leaves, which made with the meridian the following 
angles, viz.— Seven made angles greater than 35°; fifteen, angles be- 
tween 35° and 20°; sixteen, angles between 20° and 8°; twenty-eight, 
angles between 8° and 1°; and twenty-five, angles less than 1°. Of the 
sixty-nine angles less than 20°, the mean is N. 33' H., i.e. about half 
a degree east of the meridian. The error of azimuth, from want of 
means to determine the time accurately, may have been as much as 
three times this quantity. One half the leaves bore within about half 
a point of N., and two-thirds within one point. The magnetic declina- 
tion was about 6° E., and the observations were made when the sun 
was about on the magnetic meridian. 
Henna (Lawsonia inermis), a plant which has been so long used in 
Keypt as a cosmetic and dye stuff, has been introduced into com- 
merce by MM. Gillet and Tabourin, of Lyons. According to the 
‘Coloriste Industriel,’ the researches of these chemists show that the 
active colouring principle is nothing more than a peculiar kind of 
tannic acid, which they propose to call hennatannic acid. The dried 
leaves of henna contain half their weight of this substance. The plant 
is, it appears, particularly useful for imparting to silk the different 
shades of black, the colours so obtained being very beautiful and per- 
manent. 
At the Academy of Sciences of Vienna Dr. de Vry exhibited some 
beautifully-crystallized resin of the upas tree (Antiaris toxicaria), also 
the upas poison itself in a crystallizable state. He regarded the 
poison as a Glycosite, that did not act upon the stomach as a violent 
poison, perhaps not as a poison at all, and possessed poisonous pro- 
perties only when brought into immediate contact with the blood. He 
had convinced himself by repeated personal experiment that the stories 
of the poisonous atmosphere of the upas tree are fabulous. 
Further investigations into the milk vessels of Leontodon (the com- 
mon dandelion) by Dr. August Vogt, of Vienna, show that the inter- 
cellular substance occurring in the root consists chiefly of pectose, the 
same substance which occurs in unripe fruits, and in turnips and car- 
rots ; so that itis not a secretion, but a product of conversion of the cel- 
lulose of the cell-membranes, of a chemical nature. The milk vessels 
occurring in the dandelion are amongst the most ramified which occur 
anywhere in plants, springing from main stems, then ramifying and 
forming ultimately large reticulated systems around the woody nucleus. 
On examining into their origin, it appears that their main stems are 
produced by the amalgamation of the so-called conducting cells 
which accompany the bundles of milk vessels, and probably constitute 
the organ for conducting back the juices elaborated in the leaves. 
This fusion is induced by the conversion into pectose of the mem- 
branes of the cells, consisting at first more or less entirely of cellulose. 
Some interesting observations have been made by Henrici on the 
functions of roots in supplying water to the plant, and on the develop- 
ment under certain conditions of special roots destined for this pur- 
pose, to explain the frequent occurrence of plants sending roots into 
