JVafural History, 219 



delicate and difficult to raise. The first was covered with a clear 

 transparent glass shade; the second with a roughened glass shade; 

 and the third with a similar cover enveloped entirely in black 

 cloths. The garden pots were placed in vessels of water, so that 

 the surface of the earth should be constantly humid. On the 

 9th of the same month, the seeds, deprived of light, began to 

 grow; on the 12th, the radicles of those under the ground glass 

 just began to appear; and on the 15th, none of the seeds under 

 the clear glass cover, had exhibited the smallest signs of vegeta- 

 tion ; in most of them, the embryo appeared to have resisted the 

 action of moisture, and not even to have swelled under its en- 

 velopes. — Bull. Univ. D. xiii. 310. 



11. Luminous Points in ike Horizon. — The following is part of 

 a letter to the Baron de Zach. *' Permit me to communicate to 

 you a discovery which I made about six years since, but which 

 I did not make known to you before, until I had assured my- 

 self of its reality ; I beg you to make it known, if possible by 

 some of the journals. For these last six years, I have been occu- 

 pied in making observations on the clearness of the atmosphere 

 by day and by night. This gave me the opportunity of remark- 

 ing a singular light towards the north-east and the south-west. 

 It very much resembles the zodaical light, but it is always ob- 

 served in the magnetic meridian. It is more luminous towards 

 the north-west, than in the south-east : even when the sky is 

 covered with clouds, if they be equally diffused, this magnetic 

 light may be seen towards the north west, insomuch, that I have 

 sometimes been in doubt whether it was not a distant fire. To 

 be convinced of the truth of this appearance, it is only necessary 

 that the observer should have a free horizon, and that he attend 

 continually to the clearness of the air. It is requisite that the 

 eyes should be accustomed for a while to this kind of observation, 

 that they may be enabled clearly to see the phenomenon." — Bib, 

 Univ. xlii. 272. 



