Notes . 
183 
To facilitate repetition of the experiments, I give a few details as to 
the application of the guaiacum test. The tincture is prepared by 
dissolving the resin in absolute alcohol, to a deep brown solution : 
fresh tincture should be made from time to time, as it is liable to lose 
with age its property of turning blue when oxidized, especially if it be 
exposed to light. When the test is about to be applied, a small 
quantity of hydrogen peroxide, not enough to cause a permanent 
precipitate, should be added to some of the guaiacum tincture. A few 
drops of the mixture are then poured on to some of the liquid to be 
tested, either in a test-tube or on a piece of white porcelain. Boiling 
destroys the activity of all vegetable liquids. With regard to testing 
for ‘ leptomin ' in the tissues, the tissue must first of all be freed 
from oxydases, as Raciborski points out, either by heating to 6o° C., 
or by keeping it for a time in absolute alcohol : but the stay in 
alcohol must not be too long, otherwise the property of decomposing 
hydrogen peroxide will also be destroyed. The tissue is then to be 
treated with the mixture of guaiacum tincture and hydrogen peroxide, 
when a blue colour will appear in the tissues containing ‘ leptomin.’ 
I may add, in conclusion, a few further observations of my own as 
to the distribution of ‘ leptomin/ or bodies of that class, in plants. 
I find that pine-apple juice gives a strong reaction, whilst the juice of 
oranges, lemons, and apples gives no reaction : the pulp of the apple, 
and still more its rind, gives a slight reaction. Non-drying oils, such 
as olive, almond, colza, and rape, give the reaction, but not the drying- 
oils, such as linseed, walnut, and poppy. The behaviour of different 
kinds of wheat-meal is striking : bran gives a good reaction when 
a little is sprinkled on a few drops of the mixture of guaiacum and 
hydrogen peroxide ; ‘ toppings ’ and ‘ middlings ’ give a strong reaction, 
whereas the pure flour gives little or no reaction. 
S. H. VINES. 
Oxford. 
ON THE ANATOMY OF THE STEM OF DALBERGXA 
PANICULATA, EOXB. — For some time it has been known that 
the stem of Dalbergia paniculata , Roxb. exhibits certain anomalies as 
to its structure. Brandis 1 writes thus concerning this plant : — ‘ A 
1 Brandis, Sir Dietrich, The Forest Flora of North-west and Central India : 
London, 1874, p. 151. See also Gamble, J. S., A Manual of Indian Timbers: 
Calcutta, 1881. 
