56 
Walter Gardiner. 
ings it may ho stained and mounted. As a staining rcagent eithor IIoff- 
mann’s violot or preferably Hoffmann’s blue may ho used. In the caso of 
Hoffmann’s violot the seclion is quickly stained, washed in water and tlien 
placed for 24 hours or more in di lute glycerine vvhich dissolves out a great 
portion of the dye from the stained cell-wall and at the satne time removes 
the peculiar staining of the pits which, if allowed lo remain, is apt to lead 
to very delusive results. I he seetion is finally mounted in glycerine. 
When Hoffmann’s blue is used a moderate quantity of the dye is dis— 
solvcd in a 50°/o solulion of alcohol to which has been added a few drops 
of acetic acid. After staining, the sections are washed in water and mounted 
in glycerine. Or a sufficient quantity of the dye may be dissolved in a 50% 
solution of Alcohol which has been saturated with Picric acid, until the 
solution assumos a dark greenish blue tint. This solution — the properlies 
of which will be dealt with under the head of Chlor-Zinc-Jod. — l shall 
speak ol as Picric IIoffmann’s blue. After staining, the sections are washed 
in water and mounted in glycerine as before., or öfter treatment with alcohol 
they may be cleared with clove oil, and mounted in Cauada balsam. 
2. Chlor-Zinc-Jod. 
ln Tangl’s method, which was the same as Hanstkin had employed for 
demonstrating the Perforation of the sieve-plate, sections of endosperm 
were stained with Jodine and mounted in Chlor-Zinc-Jod. In such dry 
lissue as that of ripo endosperm cells, the cell-walls do not turn blue but 
merely remain stained with the ordinary yellow brown due to Jodine. The 
protoplasm on the other hand assumes a very dark brown colouration and 
aftcr some time there comes into view a series of striac tfaversing the 
thickened cell-wall which from their colouration, and from the fael that 
their depth of staining varies pari passu with that of the protoplasm, are 
laken to be esseulially protoplasmic in character. 
Although in such cases whero it can be applied the method is of great 
value, it wdl be seen that it is attended also with some disadvanlagcsj for 
lirstly, in tissues containing a higher percentage of water the walls assume 
the ordinary cellulose blue, which at once prevents the threads from being 
seen, and secondly, on account of the extensive and very varied') staining 
properties of the Jodine tho results obtained by it alonc cannot be taken as 
entirely conclusive. Nevertheless, where practicable, Tangl’s method is of 
great use lo give at least an idea of the existenee of the protoplasmic fila- 
ments, and moreover the staining of tho threads with Jodinc is mueli more 
dislinct than with any other reagenl I have yet been able to employ. 
1) Thus besides its well known reactions with protoplasm, cell-wall and starch 
Jodine givos a blue colour willi mueilage, with the cell-walls of cerlain fungi, with the 
Phloem of tycopodium, with tho cell-walls of the endosperm cells of Paeonia officinalls 
(Vines) and of Ardisia crcnulata and Ardisia polytoca (Garbineh). 
