I 
EFFECT OF THE TOTAL ECLIPSE OF THE SUN UPON PLANTS. 
OJST THE EFFECT OE THE TOTAL ECLIPSE OE THE SUN, JULY 28, 1851, UPON 
THE VEGETABLE KINGDOM* 
By Professor E. MEYER, or Konigsberg. 
BURING last winter Dr. Basch, the Director of our Observatory since the death of Bessel, gave to 
our Physical Economical Society a lecture, which was soon after printed, " On the Total Eclipse 
of the Sun on the 28th of July, and the phenomena which are then to be expected." He says : — 
" Twining plants, Mimosas, and other plants very sensitive to light, have been seen to close (during 
former total eclipses) and to open again at a certain time after the obscurity had passed off. In 
France, in the year 1842, so strong a dew was observed directly after the total obscuration, that drops 
could be perceived upon the margins of leaves. The thermometer began to sink, the so-called eclipse- 
wind arose, which blew over the surface of the earth in the direction of the course of the darkness," &c. 
This information rendered it my duty to take particular notice of the behaviour of sensitive plants 
tluring the ensuing total eclipse, although I could not promise myself any great results. The eclipse 
was to begin here in Konigsberg at thirty-seven minutes and eleven seconds after three o'clock, and 
end at thirty-seven minutes and fifty-four seconds after five, therefore would occur at a time of the 
day at which many of the plants more sensible to light usually close their flowers. The total obscura- 
tion of the sun was to occur at thirty-eight minutes and five seconds after four o'clock, and only last 
for three minutes and one second. It seemed to me very improbable that so short a withdrawal of the 
light, however intense the darkness might be, would make any noticeable impression upon the plants. 
Experience confirmed my expectations, yet I may give a brief report of the observations. 
The south side of my dwelling is covered by a vine, and therefore docs not radiate heat, and there 
I collected upon a long table all the potted plants which it appeared desirable to observe, and also some 
flowers which I could not arrange in pots, such as Calystegia davurica, in cut specimens, in glasses of 
water. Other plants growing in the earth were close enough to the place of observation. The thermometer 
was suspended on the east side of the house, within a few steps of the place where the plants stood. 
At the commencement of the observations the thermometer stood at 16.1° Reaumur (about 66° 
Fahr.) and attained its lowest point 13.4° Reaumur (about 62j° Fahr.) about fifteen or eighteen 
minutes after the end of the total obscuration. From that time it rose again, and reached exactly its 
original point in a short time. During the total obscuration the darkness was so intense that no 
shadow was visible, and planets and fixed stars of the first and second magnitude were distinctly 
observed. In my station, sheltered from the north, but situated tolerably high, I perceived nothing 
of the eclipse-wind, which should have come from the north-west. Neither did any production of dew 
upon the plants occur. I was obliged previously to the obscuration to bring Mimosa pudica and pros- 
trata from the open air, inside the window of a room having a south aspect, because every breath of air 
caused these stove-raised plants to close up. In-doors they soon opened, and the eclipse excited no 
influence over them ; they did not close again till evening. Just as unmoved, in the open ah', remained 
the pinnate leaves of Acacias, of Porliera hygrometrica, and others. 
Many of the selected plants did not close then- flowers till evening, and others before half-past 
three, or very soon after, when the diminution of light was scarcely perceptible, therefore proving 
useless for observations of this kind. Convolvulus Oneormn began to close its flowers before the eclipse, 
and the closing was not completed until long after it ; but Calystegia davurica and Ipomcea coccinea 
remained open until evening. Cistus laxus (the only one completely in flower) behaved like Con- 
volmdus Cneorum, but the closing of the flowers began later, shortly before the total obscuration, and 
required a longer time. With regard to Helianthemum hirtwm, I am doubtful whether the total 
eclipse acted on it ; most of the flowers closed and shed their petals during it, but several not until 
later in the evening. The only distinct influence I observed was in the flowers of Oxalis rosea and 
Bridgesii. Both remained open until the total obscuration of the sun, and then closed rapidly, not, 
however, opening again. I made a counter-experiment with both another day. I placed them, com- 
pletely open, in the shade at ten o'clock, and found them closed by eleven ; I brought them again into 
the sun ; once more I placed them in the shade with the same effect ; but when I again placed them 
in the sun, about five o'clock, they opened no more. A reporter for the Times, who came here to 
observe the eclipse, but whom I have not myself met, stated that he saw Eschscholtzia californica and 
Nemophila atomaria close at the total obscuration. I did not observe the Eschscholtzia myself, but 
the Nemophila was in flower in a thick bed near me. I cannot assert that no flowers closed, but the 
greater part remained open until evening. I state this lest my observations should be questioned on 
the above authority. 
» From the Sotanische Zeitang, Aug. 15. (([ 
