ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
177 
Tests for Ligneous Tissue.* — Dr. F. Zctzsche enumerates twenty- 
eight different methods which have been used and recommended by vari- 
ous experimentalists for the detection of woody tissue. Out of these the 
following eight are commended: — (1) indol with hydrochloric acid; 
(2) phloroglucin-hydrochloric acid ; (3) carbazol-sulphuric acid ; (4) 
anilin sulphate ; (5) toluidin-diamin-hydrochloric acid ; (6) ammoniacal 
fuchsin; (7) Bismarck-brown-lisematoxylin ; (8) solid-green deltapurpurin. 
The best results are obtained from the following : — (1) The indol- 
hydrochloric reaction gives a brick-red to chocolate-brown colour ; may 
be used successfully in from 1/100 to 1/1000 per cent, solution; and 
has the great merit of allowing the objects to be mounted in glycerin 
and in balsam. (2) Phloroglucin is used in 2—3 per cent, alcoholic 
solution, together w T ith an equal volume of dilute hydrochloric acid. 
The colour is brownish -red. Preparations do not mount well in either 
glycerin or balsam. (3) A mixture of equal volumes of alcoholic solu- 
tion of Bismarck-brown and Bohmert’s hasmatoxylin has the special 
merit of not requiring differentiation, but care must be taken not to 
overstain. Lignification is shown by the brown staining, the non-ligneous 
tissue being blue. The preparations should be mounted in glycerin- 
gelatin. (4) The ammoniacal fuchsin solution is made by freely diluting 
a saturated alcoholic solution of fuchsin with water, and then adding 
ammonia until the fuchsin just begins to precipitate. The objects are 
immersed therein for 1/2 minute, and, after having been well washed, 
are contrast-stained in saturated anilin-blue solution (1 minute). After 
dehydration in alcohol they are mounted in balsam. 
The intensity of lignification is determinable by the use of solutions 
of phloroglucin-hydrochloric acid, of varying strengths, allowed to act 
for a definite time. Three minutes is suggested as the time limit, and 
1/40 to 2 percent, for the solution. The latter is made by dissolving 
the phloroglucin in 1 vol. of 90 per cent, alcohol and 1 vol. of strong 
hydrochloric acid. The phloroglucin is first dissolved in the alcohol, 
and the acid afterwards added very gradually in the cold. 
Eight degrees tf lignification are made by the author from this 
method, at the top of the list standing Abies pectinata , at the bottom, 
Musa paradisiaca. 
Demonstrating Presence of Agar.j — According to Herr G. Marp- 
mann, there are many edible alga3 in tropical seas. These belong to 
the group of Floridem, with red, lcaf-like or membranous growth and 
upright thallus. Among these are Gracilaria lichenoides Ag., Eucheuma 
spinosum and E. gelatmse Ag. All these, when boiled with water, pro- 
duce a thick jelly, which in the dried condition is known as agar-agar. 
This agar appears to be chemically identical with the alga-mucus of 
Gclidium corneum. The agar jelly and Gelidium jelly, dissolved in 
boiling water, filtered through cotton-wool and precipitated with alcohol, 
form horny masses when dried, the former being known as gelose, the 
latter as gelinose. 
As pectin, or vegetable jelly, appears to be of the same, or very 
nearly the same chemical composition as agar, and as fruit jelly is often 
adulterated with agar and gelatin, it becomes important to have a ready 
test to distinguish the presence of agar. This may be done micro- 
* Zeitsclir. f. ang. Milcr., ii. (189C) pp. 225-3G. f Tom. cit., pp. 257-G1. 
1897 N 
