IV. On tho conlinuity of the protoplasm through the walls of vegetable cells. 55 
research viz. Melliylene blue which cspccially stains Ihe coli-wall, and 
Hoffmann’s Idue 1 ) vvhich cspecially colours the protoplasm. The only pre- 
cautions rcquircd are that a fairly dilute solulion of the dye should he made 
in Alcohol of a strength not greater than 50 per cent, and that the stained 
seclion should he washed in water 2 3 ). 
All experirneuts made with the view of attempting lo detect the pre- 
sence of protoplasmic (ilaments in the cell-wall when the wall was normal 
and intact inet with hui little success 4 ), so that in investigaling the suhject 
of protoplasmic continuity the method of swelling the cell-wall, and subse- 
queully staining with a dye wliich was found lo especially stain the prolo- 
plasm, was adopted. Either Sulphurie acid or Chlor-Zinc-.lod. was used 
as the swelling agenl, allhough every preference was given lo the (aller. 
Naturally I’otash might have been used, hut on accounl of the diflicuIties 
which allend the thorough washing out of that reagenl and in consequence 
of its oftou doleterious action on the dyes, il was rejecled w hen it w as found 
that Chlor-Zinc-Jod. answered every purpose. Sinee for the lwo reagents 
employed the inethods are somewhat different it seems best to treal of them 
separately. 
1. Method with Sulphurie acid. 
Düring the earlier pari of my work 1 was accuslomed lo use Sulphurie 
acid, in comhinalion with Hoffmann’s Violet. This latter reagenl, al the time 
of staining, colours equally hoth protoplasm and cell-w all. lf how ever the 
seclion he trealed for some time with dilute glycerine, the staining of the 
cell-wall is removed, and the protoplasm alone remains clearly stained 4 ). 
ln working with Sulphurie acid, the fresh material is first cut in water. 
A seclion having been taken up with a plalinum spatula and the excess of 
w ater removed w ith hlotting paper, a drop of slrong Sulphurie acid is placed 
upon it, and allowed to act for a short time — usually a few seconds. The 
section is then plunged into water and rapidly washed. After several wash- 
1) Sioce tho various aniline dyes evon though possessing the same name dilTer 
materially in their staining reactions, 1 may montion that Ihis parlieular blue is known 
as IIoI'I-masn’s blue (Aniline biuo) and may bo obtained from Monr.u.i in Würzburg. 
2) Like Mayer (‘Mittheilungen aus der Zoologischen Station zu Neapel’. Vol.li 1880) 
I found (hat dyes containing a high percentage of alcohol stain more diffusely tlian those 
of weaker grades. 
3) ln certain instances where the threads were well developed, e. g. Bontinekia, 
Tamus etc. the threads can bo distinguished when the sections are meroly mounted, 
in water, or dilute glycerine & if a little Jodine bc added they are very clearly brought 
into view. This is a very important point, and proves that the phenomena dctailed in 
the present paper are not artilicially induced by reagents. 
4) A very useful reagent for the demonstration of sieve-tubes may be made by dis- 
Solving the IIoffmann’s violet in strong Sulphurie acid. After treatrnent with this solution 
the sieve-tubes are well brought into view, and moreover all lignitied tissue assumes Ihe 
usual gold yellow tint, as alter treatrnent with Aniline Chloride and hydrochloric acid. 
