The Utilization of Herbarium Material. 107 
acid may be shaken up first with ordinary bleaching powder, the 
excess of whicli is removed by filtration. 
Dehydration, embedding and sectioning are performed normally. 
Staining presents slight difficulties. The solvent action of Potash 
upon the lignin substances affects the reactions which lignified 
walls should display. They do not, for example, give the familiar 
red colour with Phloroglucin. 
I have not tested a range of stains from this point of view, 
because I found Fuchsin perfectly satisfactory. An aqueous 
solution (2%) may be employed in the usual way, the tissues being 
subsequently differentiated by acid alcohol; or a solution of 
Fuchsin decolourized by the addition of Sulphurous Acid may be 
used, which has a specific and direct affinity for lignified tissue. 
Stain in this solution for 10-15 mins. Wash in tap-water until 
excess of acid is removed. If more Fuchsin becomes oxidized 
during the washing out it may be removed by treating the sections 
with Absolute Alcohol. Counter stain with a saturated solution of 
Light Green in Clove Oil. 
University College, 
Reading. 
October , 16t1i, 1915. 
LITERATURE. 
1. Tunmann. Pflanzenmicrochemie. Berlin, 1913. 
2. Zimmermann. Botanical Microtechnique. English translation by J. E. 
Humphrey. New York, 1893. 
3. Lagerheim. Ueber die Anwendung von Milchsaure bei den Untersuchung 
von trockener Algen. Hedwigia, 1888. p. 58. 
