MEMOIRS. 
On the CoLour of LEAVES at DIFFERENT Szasons of the 
Year. By H. C. Sorsy, F.R.S., &c. 
THE number of distinct vegetable colouring matters is so 
great, and there are so many plants which merit careful 
examination, that any general conclusions I might now form 
would probably be considerably modified by further inquiry. 
This makes me hesitate in giving a decided opinion on many 
questions connected with my subject; but, at the same time, 
1 feel that it is better to run the risk of making some errors 
than to describe the facts without uniting them by such an 
amount of theory as may serve to lead to intelligible general 
principles. I shall, therefore, endeavour to draw such con- 
clusions as the present state of the subject admits, and beg 
my readers to place no more value on them than I do myself, 
and to look upon them as provisional, to be modified as our 
knowledge increases. 
It would make this communication far too long if I were 
to explain in detail how all the various different coloured 
substances may be identified or distinguished by their 
spectra, previous to, or after, the addition of suitable re- 
agents, and must therefore refer to my papers already pub- 
lished,! confining myself now chiefly to what is new or requi- 
site in connexion with the subject before me; but, at the 
same time, must mention numerous well-known facts, which 
may not have been looked upon from my particular point of 
view. 
As I have explained in some of my published papers, it is 
' 1. “On a Definite Method of Qualitative Analysis of Animal and 
Vegetable Colouring Matters by means of the Spectrum Microscope.” 
(‘ Royal Soc. Proceed.,’ xv, 1867, pp. 433—455; ‘ Phil. Mag.’ (4th ser.), 
xxxiv, 1867, pp. 144—166.) 
2: “On the Colouring Matters of Blue Decayed Wood.” (‘ Quart. 
Journ. of Micros. Science,’ IX, 1869, pp. 43, 44.) 
3. “On some Technical Applications of the Spectrum Microscope.” 
(Ib., pp. 358—383.) 
4. “On the Colouring Matters derived from the Decomposition of 
Minute Organisms.” (‘ Monthly Micros. Journ.,’ ili, 1870, pp. 229—231.) 
5. “On the Various Tints of Autumnal Foliage.” (‘ Quart. Journ. of 
Science,’ XXIX, 1871, pp. 64—77.) 
VOL. XI.— NEW SER. P 
