APPENDIX II 685 
produced if sections containing inulin are first treated with a 
drop or two of this reagent and then, after a minute, a drop or 
two of sulfuric acid be added. 
- PerROLEUM EtHEer.—Useful in clearing sections or powdered 
material of oil. 
PHLOROGLUCIN SOLUTION.—Dissolve 1 Gm. of phloroglucin 
in 50 cc. of 95 per cent. alcohol. This solution gradually darkens 
and loses strength with age. It is unfit for use after three or 
four months. The lignified walls of elements first treated with 
several drops of this solution and subsequently with a drop or 
two of concentrated hydrochloric acid are colored red. 
PorasH SoLutTion.—Several percentage solutions are em- 
ployed in histological technique for varying purposes. ‘The most 
commonly used one is the 5 per cent. aqueous solution which is 
used for clearing sections of starch, protein and tannin. Ten to 
20 per cent. aqueous solutions are used for the purpose of sepa- 
rating the epidermis of leathery leaves. The leaf material is 
boiled in the strong potash solution until the epidermis puckers 
up in the form of blisters, when it should be removed to a slide 
and the epidermis lifted off by means of a fine forceps or dissect- 
ing-needles. A 2 per cent. solution is used for the isolation of laticiferous 
vessels from plant organs. Pieces of stems, barks or roots containing 
these elements are placed in a test tube and digested on a water- 
bath for a half hour or longer until the parenchymatous tissues 
are sufficiently soft. The potash solution is then poured off and 
the material washed with water, transferred to a slide and the 
woody or other undesirable parts removed with the aid of dis- 
secting needles. The softer parts are then stained with iodine 
and potassium iodide solution; a cover slip is adjusted, the slide 
placed on stage, and the laticiferous tissues are identified by the 
presence of branching and anastomosing tubes stained yellow to 
yellowish-brown with granular contents. A 1.5 per cent. solu- 
tion is used for the digestion of ground cereals or wheat middlings 
for the purpose of clarification preparatory to microscopical 
examination of these materials. 
PoTasstUM FERROCYANIDE.—A 10 per cent. solution is 
ed in studying the localization of alkaloids in plant 
employ 
materials. Sections of fresh material are fixed, in order to pre- 
