644 
SUMMARY OF CURRENT RESEARCHES. 
solution of picrocarmine, and after having been allowed to stain for 
24 hours or so is examined. In case of suspected amyloid disease 
methyl- violet may he used instead of picrocarmine. Permanent pre- 
parations may he made by mixing the stained deposit with Farrants’ 
medium and allowing the mixture to stand for three or four days, and 
then mounting a specimen from the deposit. 
(6) Miscellaneous. 
Microchemical Reaction of Vegetable Albumen.* — Dr. A. De Wevre 
studied the microchemical reactions of vegetable proteids in specimens 
rich in reserve-albumen, such as the pea, castor-oil plant, maize, and 
wheat; also in Cucurbita pepo, Carica Cundinamcircensis, and some 
other plants. The reagents in their action are considered under three 
divisions — coagulating, precipitating, and colouring. The author arrives 
at the following conclusions : — 
(1) Albuminoids cannot be localized by means of a single reagent ; 
several are needed. 
(2) Before testing, sections must be boiled in water, then in absolute 
alcohol, or he immersed in tartaric acid alcohol. 
(3) The most sensitive reagents are, in order of sensitiveness : — 
a. Iodopotassic iodide, or a solution of eosin. b. Millon’s reagent. 
c. Picric acid, xanthoproteic acid, phosphomolybdic acid : Guezda’s test 
(saturated ammoniacal solution of sulphate of nickel gives blue colour 
turning to orange-yellow with KHO). d. Pietrowski’s test (biuret 
reaction), c. Eeichel and Mikosch’s test (alcoholic solution of benzal- 
dehyde plus H 2 S0 4 , containing a trace of ferric sulphate). If all the 
tests give a reaction, the presence of albumen is assured. 
(4) Absolute alcohol is the best coagulating reagent. 
(5) The xanthoproteic reaction answers best for the examination of 
porous tissue, “ tubes cribles,” &c., and the same may be said for eosin. 
(6) The reactions from porous tissue are frequently not very marked. 
(7) At the growing ends of roots and in the laticiferous vessels of 
various plants is a great quantity of proteid substances. 
* Bull. Soc. Beige de Microscopic, xx. (1893-94) pp. 91-121. 
