674 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
corrosive sublimate for fixing tlie leucoplasts, e. g. in the epidermal 
cells of the leaves of Tradescantia discolor ; the leucosomes themselves 
not being in any way changed by the sublimate. Good results were 
also obtained — though not so good — with concentrated alcoholic 
solution of picric acid, and with alcohol alone. With small pieces this 
immersion in the sublimate solution is sufficient. To prepare for the 
microtome they should then be placed first in pure alcohol, then for 
twenty-four hours in a mixture of three parts xylol and one part alcohol, 
then as long in pure xylol, then in a solution of paraffin in xylol saturated 
in the cold, finally in pure paraffin. For staining, Altmann’s method * 
with acid-fuchsin was found to be the best ; but a special modification 
of it is described in detail. Iod-green, cyanosin, and dahlia may also 
be used. 
For fixing the cell-granules the author uses either a concentrated 
alcoholic solution of picric acid or 3 per cent, nitric acid. They may 
then be stained with acid-fuchsin by Altmann’s method, which colours 
the granules an intense red, while the chloroplasts and nucleus are left 
quite colourless. 
For staining the proteid-crystalloids, a method is employed termed 
by the author the acid-fuchsin method B. The section is first of all 
dehydrated by alcohol, and then placed in xylol or in xylol-Canada- 
balsam. The leucoplasts are fixed by picric acid or sublimate, and the 
section then stained with acid-fuchsin. While the nuclei and nucleoli 
remain perfectly uncoloured, the crystalloids take up an intense red. 
Good results were also obtained by the ordinary Altmann’s acid-fuchsin 
method ; also by fixing with concentrated aqueous or alcoholic solution 
of sublimate, aqueous or alcoholic solution of picric acid, 5 per cent, 
solution of potassium bichromate, or with Muller’s fluid. 
(3) Cutting-, including Imbedding and Microtomes. 
Imbedding Vegetable Preparations in Paraffin.f — Herr L. Koch 
discusses at great length and with copious detail the proper method of 
imbedding vegetable preparations in paraffin. After a critical survey of 
various methods of paraffin imbedding, the author gives a general outline 
of his views on the subject, and then proceeds to give the minutiae 
requisite for obtaining a satisfactory result in special cases. His views, 
however, are tolerably simple, and do not seem to differ materially in 
practice from those of other people who apply themselves to vegetable 
anatomy. 
The general proposition, on which much stress is laid, and the obvious 
inference therefrom, is one which occurs to any person after a very small 
amount of practice. It is that the imbedding mass must be made to 
penetrate into cells and intercellular spaces, and in order to do this the 
air and water must be thoroughly and completely removed. This is 
effected by immersing the objects in spirit, the strength of which is 
gradually increased up to absolute alcohol. The objects are then satu- 
rated with paraffin dissolved in chloroform. The saturation is effected 
by gradually increasing the thickness of the paraffin mixture ; when a 
* Cf. this Journal, 1888, p. 147. 
f Jahrb. f. Wiss. Bot. (Pringsheim), xxi. (1890) pp. 367-468. 
