PROTOPLASM THROUGH THE WALLS OF VEGETABLE CELLS. 
847 
apparent diameter. That this is actually the case may be demonstrated either by 
reversing the operation and staining with iodine after treatment with Chlor. Zinc Iod. 
and subsequent washing, or by staining with picric-HoFMANN’s-blue. (Compare 
Plate 69, figs. 22 and 23.) 
As a rule nothing can be seen of the threads when a section of endosperm tissue is 
mounted and stained in the usual manner. But to this statement BentincJcia affords 
an exception, for here an appearance of striation can be detected, and in Stevensonia 
staining with Hofmann’s violet alone makes the threads apparent. Treatment with 
iodine, picric acid, or with a mixture of iodine and glycerine will also often bring them 
into view, eg. — Lodoicea (Plate 69, fig. 20), Latania , and BentincJcia. 
Experiments with the object of injecting the threads with colouring solutions met 
with no success. Pieces of the endosperms of Latania and Calamus were fitted into 
a bored india-rubber cork, which was then tightly fastened into one end of a 
manometer tube, the shorter arm of which contained the solution of the colouring 
matter, and the longer held the mercury by means of which the injection-pressure 
was induced. First, a solution of water-blue in water was employed, and as this 
caused swelling of the wall a solution of insoluble blue in alcohol was used in 
preference. However, when exposed to the pressure of a column of mercury of sixty 
inches no injection occurred. 
Besides the particular methods I have chosen for the elucidation of this subject, 
many others were tried with little or no success. Sections of BentincJcia, as being 
favourable material, were treated in the usual way with solutions of gold chloride and 
silver nitrate, but with no result. In every case it was found that it was necessary 
to swell the cell-wall before staining. After swelling with Chlor. Zinc Iod. and 
washing, silver nitrate was again tried, and this time with some small amount of 
success. I adopted a modification of treating the section with sulphuretted hydrogen- 
water, after exposure in a 2 per cent, solution of silver nitrate for half-an-hour, and 
subsequent washing, instead of reducing the silver by the action of light, as in the 
usual process. The result was perhaps better, but still far from satisfactory, and 
would be quite inapplicable in any case where the threads were not particularly well 
developed. Some sections, after swelling, were treated with an alcoholic solution of 
tannin, and when washed were shaken up with a solution of ferric chloride. The wall 
then coloured the usual blue-black, and the colourless threads could be seen fairly 
well. Other sections, again, were soaked in a solution of ferric chloride, and after 
washing were treated with a solution of potassium ferrocyanide. In this case the 
threads were less clearly defined than with tannin and iron. Lastly, sections were 
treated for some time with a solution of corrosive sublimate, in the hope that an 
insoluble compound might be formed with the remains of the cell protoplasm. After 
washing the section was shaken up in sulphuretted hydrogen-water, but with no good 
result. Thus all these experiments pointed to the fact that my methods, if not 
perfectly satisfactory, were at least fairly successful. 
5 Q 2 
