THE PRINCIPLES OF BIOLOGY. 
309 
tannin reaction, the strength of the reaction depending on 
the strength of the tannin solution in which they had lain. 
That this was not due to a film of tannin in the grain I 
showed by rapidly washing grains in alcohol, when the grain 
still gave the tannin reaction; and the use of iodine on 
similar grains showed the tendency to the same red colora¬ 
tion, which I have noted in starch-containing cells of Quercus. 
Hartig’s “ Gerbmelil ” is, therefore, starch, into the inter- 
molecular reticulum of which the solution of tannin in which 
they were lying had penetrated. 
Some further light may be thrown on this by the case of 
Acer Pseudoplatcinus. In the cells of the pitli-crown I 
observed (October 22nd), in several specimens, the starch 
grains, after the action of iron chloride, surrounded by a 
cloudy blue coating. In the same species, on December 20tli, 
the phenomena presented by Quercus pedunculata were sub¬ 
stantially repeated in a large number of cells in the median 
portion of the pith-crown, where fluid tannin was earlier, 
and was then, most abundant. The same phenomenon was 
observed, though not followed out, in Populus arujulcita. Its 
distinctness in Quercus is probably due to the large quantity 
of tannin present. 
(To be continued.) 
THE PRINCIPLES OE BIOLOGY.* 
BY HERBERT SPENCER. 
Exposition of Chapters IX., X., and XI. 
Coincidence between High Nutrition and Genesis. 
Specialities of these Relations. 
Interpretation and Qualification. 
(Abstract.) 
BY W. R. HUGHES, F.L.S. 
Mr. Herbert Spencer reminds us in the opening chapter 
(IX.) that we have seen “ that after individual growth, develop¬ 
ment, and daily consumption have been provided for, the 
surplus nutriment measures the rate of multiplication. This 
surplus may be raised in amount by such changes in the 
* Transactions of the Birmingham Natural History and. Micro¬ 
scopical Society, Sociological Section, read December 9th, 1886. 
