236 Transactions of the Royal Microscopical Society. 
Fig. 9. — Young Leaves of Same. 
M. 
\. 
Observations. 
1 
23-97 
Centre 
651-0 
Class 1. Very black; size -37. 
2 
22-7 
» 
598-5 | 
„ 2 . „ dark at one end, 
other shaded; size - 2 . 
3 
20-07 

531-5 
„ 1 . Dark ; size 1 35. 
4 
19-00 
498-0 
„ 1. Shaded; size ' 6 . 
5 
19-50 
Commencement 
482-5 
General absorption. 
Fig. 10. — Ked Leaves of Same. 
, • o ( General absorption; very shaded 
Commencement 1 515-5 \ at first till quite black; no trace 
r | of any ordinary bands. 
The action of the rise and fall in temperature, besides the 
beautiful way in which it is disseminated throughout the whole 
spectrum, has without doubt great influence in the production of 
both plant life and decay. All who take any interest, however 
small, in the plot of garden which, notwithstanding the advance in 
population about the district in which they happen to be located, is 
still reserved to them, must know how useful an acquisition the 
cool corner is ; all things seem to vegetate so much better there, 
besides acquiring that amount of strength which is often wanting 
in the same species not thus suitably situated. 
With all this, however, the leaves of laurel, holly, and arbutus, 
when in a dying state assume a more or less yellow tint, which 
seems indeed the most universal form of colour for all plants 
whether of the evergreen species or not. This yellow substance, of 
which the partially dead leaves are composed, is acted upon by 
temperature to a great extent. They soon, as is far too common a 
metamorphosis to require any allusion, become a dull dead appear- 
ance, besides being very brittle and breaking off from the stem 
with the merest touch. Thus we are led to see in conclusion how 
that the combined action of both light and heat has done its last 
duty, and what remains is only so much carbonized matter. 
This, then, closes my few remarks upon what seems, at least to 
me, a most extensive subject, and I suppose it is needless for me 
to add how much I wish to see others taking up this branch of 
inquiry. 
The further question of solvents with regard to the species of 
plants of which we have treated is a most important one, and 
I can only hope that on some future occasion I shall be enabled 
to bring before you some researches in connection with the micro- 
spectroscope, that during the working out of this paper have natu- 
rally presented themselves. 
