PROTOPLASM THROUGH THE WALLS OF VEGETABLE CELLS. 
819 
In my paper “ On the Continuity of the Protoplasm in the Motile Organs of Leaves”'"' 
I stated that when the plasmolytic condition is induced in a cell, the contracted 
primordial utricle does not lie free in the cell cavity, but is connected to the cell-wall 
by numerous fine threads of protoplasm. Since these threads are exceedingly thin 
and easily ruptured, the value of a preservative agent can be readily tested by 
observing with what degree of success it can fix the protoplasm of such a cell, and 
can preserve unbroken the delicate threads. (See Plate 70, figs. 34, 35, 36, and 37.) 
For this purpose thin transverse sections of the pulvinus of Robinia pseudacacia 
were rapidly cut in water, and treated for about five minutes with a 10 per cent, 
solution of sodium chloride. The excess of salt was quickly washed out with water, 
and the sections were exposed in a watch-glass with frequent stirring to the action of 
the fluid to be experimented upon, mounted and examined. 
The following are the principal results of those experiments :— 
With absolute alcohol all the threads were broken, great contraction taking place, 
attended by great alteration in the shape of the rounded central mass of protoplasm, 
which now assumed an irregular as opposed to a regular spherical form with a smooth 
Contour. 
With 1 per cent, osmic acid in the same way the sharply rounded contour gave 
place to an irregular, uneven outline, and general swelling of the protoplasm occurred. 
All the strings were broken. The nucleus, however, was well preserved, though 
somewhat swollen. It is possible that either a stronger solution of the acid or osmic 
acid vapour would be more successful. 
One per cent, chromic acid, with the exception perhaps of an alcoholic solution of 
corrosive sublimate, gave the least satisfactory results. None of the threads were 
preserved, and the nucleus and protoplasm had undergone great alteration of form. 
A saturated watery solution of picric acid, on the other hand, gave very satisfactory 
results indeed. With this reagent the nucleus was especially prominently brought 
into view, and the protoplasm had undergone the least change. Though in many cases 
obvious shrinking was produced, yet as a rule the rounded contour was well preserved, 
and many threads remained unbroken (see Plate 70, fig. 38). Silver nitrate after 
plasmolysis with nitre, and gold chloride were also tried, but with little success. 
As a result of these experiments it would appear that none of these reagents are 
entirely successful. In every case the protoplasm, even if killed at once, undei’goes 
more or less shrinking, attended with great alteration of form. My results as to 
absolute alcohol agree with those of Flemming, who also finds that saturated picric 
acid, and 1 per cent, chromic acid, are preferable fixing agents for nuclear inves¬ 
tigation. As to chromic acid our results differ. But whatever the reagent used, it is 
quite apparent that it is easier to deal with young cells, full of protoplasm, with very 
* Proc. Roy. Soc., November 11, 1882. 
