Application of the Micro-spectroscope, &c. B]j Thos. Palmer. 233 
gave an account of some most elaborate experiments which were 
performed by Dr. Moll. The question at stake was, “ Can leaves 
decompose the carbon dioxide which is at the disposition of the 
root ? ” He argues that one part of the plant — the leaf — taking up 
and decomposing carbon dioxide, is no proof that it is not taken 
up in another part — the root. Space will not admit of even a 
resume of his experiments, one of which, however, I must take, as 
it so especially corroborates what has been previously said in 
relation to the action of light. Leaves of bulrush and bur-reeds 
were etiolated, and then separated from the plants ; the upper end 
of the leaf was inserted in a glass shade without carbon dioxide, 
the lower in an atmosphere containing 5 per cent, of this gas, 
whilst the space between was left free to the open air, though it 
was obscured by tinfoil, so that no starch could be formed in it, at 
the expense of any carbon dioxide passing through the tissues from 
the lower shade. The experiments lasted one day and uniformly 
gave the same result ; starch was formed abundantly, where carbon 
dioxide was at disposal in the air, while the excess of it in the 
lower shade had no effect upon the portion of the leaf in the 
upper one, which remained entirely free from starch. The 
apparatus was, moreover, always placed in a light window shaded 
by gauze blinds, if the sun was too hot ; and throughout all the 
experiments it was an interesting circumstance to note that in the 
lower portions of these rather thick leaves more starch was 
formed on the side next to the window. This variation in the 
starch formation according to the amount of light showed that that 
portion of leaf had not always used all the carbon dioxide at its 
disposal, and that consequently there was an excess which might 
have passed upwards through the tissues. 
Fig. 6. — Holly in Ether. 
M. 
A. 
Observations. 
1 
22*08 
Centre 
645*0 
Class 1. Very black; size *48. 
2 
22*73 
596*0 
„ 2 . Shaded; size *335. 
3 
20*15 
„ . . . . 
528*57 
„ 1. Very shaded ; size *285. 
4 
/ 20*8 \ 
\ 19*8 / 
Commencement 
/ 504*751 
\ 473*50/ 
Very shaded, ultimately quite 
black ; general absorption. 
Fig. 7. — Holly (Variegated) Young Leaves in Alcohol. 
1 22-0 Centre .. ..I 649*0 (I CIass L V ®*y sh ^ed; size -2. 
ll Same as in Fig. 1. 
f 19*0 ) (■ 498*0 i Sll aded, ultimately quite black; 
2 1 jg.g > Commencement 1 455 - 75 ) general absorption. Same as 
I ; Eig. 1. 
Another highly interesting point in relation to this subject, and 
which is also of some importance, is the production of red leaves 
