THE MIDLAND NATURALIST. 
“ Come forth into the light of things, 
Let Nature be your teacher.” 
Wordsworth. 
COLOUR-REACTION: 
ITS USE TO THE MICKOSCOPIST & TO THE BIOLOGIST.* 
BY W. H. WILKINSON, 
HON. SEC. OF THE BIRMINGHAM NATURAL HISTORY AND MICROSCOPICAL SOCIETY. 
The rapid progress which has been made in nearly every 
branch of science during the last few years, is recognised by 
every student of Nature, and must lead to still further advance 
in the near future. Every fresh discovery made, and every 
new fact recorded, but opens a new door for fresh exploration 
and paves the way for new observation. 
Thus the microscopist is constantly being enriched by the 
advance of optical science, and gladly avails himself of the 
improvements in the illumination of the object and the power 
and penetration of his lenses, and, as we are confidently told, 
the employment of the new German glass gives still further 
promise in this direction. 
But the biologist not only needs all this, but more, and, 
while eagerly taking advantage of the improvements in optics, 
he applies to chemistry for acids and other solutions to 
disintegrate and separate and clear the various tissues he has 
to study. Thus when he has prepared delicate and thin 
sections, the chemist finds him various stains, which not only 
make his preparations look beautiful, especially in double 
Description of Plate I. 
Figure 1. — Thin section of a portion of an apothecium of a 
Lichen, Pertusaria communis , magnified 150 diameters, showing the 
asci and spores under the action of iodine. 
Figure 2.—Thallus of Lichen, Roccella phycopsis , magnified 4 
diameters. 
A. Natural Colour. 
B. Changed to Red by the action of Hypochlorite of Lime. 
* Transactions of the Birmingham Natural History and Micro¬ 
scopical Society, Microscopical Section, April 5th, 1887. 
