628 Price. —Some Studies on the Structure of the Plant Cell 
in the experiments described above, it is clear that something more than the 
mere rate of coagulation must be considered in the action of these agents 
(Lee, A. B., ’ 13 , pp. 20, 21). The appearance of the gel produced, as 
well, of course, as the rate of formation of the gel, differs considerably with 
the agents employed. In some cases, as with that of fixation by osmic 
acid described, the larger microsomes of the protoplast may remain present 
in the fixed colloid, while in other cases all identity of the microsomes is lost. 
The action may be one of absorption of the fixing agent by the colloid as 
formed. This seems to be indicated by the well-known fact that certain 
fixing agents are best followed by certain stains. It may be repeated here 
that in all cases observed the fixative has also an action on the protoplasmic 
complex in the normal and vital gel state. As fixation in most cases 
implies coagulation of a mobile hydrosol, it seems hardly possible to imagine 
a fixing agent which shall be even approximately perfect in its action. The 
resulting gel must be regarded as a complex of artifacts in the strict sense 
of the term, and whether these artifacts shall be small enough to imitate 
closely the pre-existing conformation, or shall be larger, depends on the 
perfection of the fixative. The most perfect agent is that which causes the 
least change on coagulation, and it seems that this can best be judged by 
dark-ground methods. 
There seems in many cases to be fairly good evidence to regard the 
continuous phase of the colloid complex as more or less viscous in character ; 
certainly the whole complex is in some cases distinctly viscous. This 
viscosity may be used to explain the fact that the protoplast or plasmolysis 
is often pulled out into fine fibrils connecting with the cell-wall, or adhering 
as a fine thin layer. The evidence of the appearance presented by the 
plasmatic surface or membrane and the vacuole wall has been given. 
There is no structural contradiction to Czapek’s hypothesis of the membrane 
containing a small quantity of fatty emulsion suspended in the colloid 
surface film (Tl). The argument of Lepeschkin (’ll), that as the outer 
surface of the colloid protoplast does not mix with water the membrane 
cannot consist of colloid particles distributed in a watery medium, bears 
considerable weight — there must be a continuous membrane of some sort 
apparently to prevent the escape of colloid particles. As has been shown, 
this membrane may be the hydrogel layer produced by coagulation. 
It seems hardly probable, or even possible, that pure water could be ionized 
sufficiently to produce a gel layer at the outside of a watery sol — such an 
action would mean that no ionic dissociation whatever occurred in the 
colloid. The very dilute solutions which enter the cell continuously may 
serve to produce and maintain such a layer. It is an interesting fact that 
pure distilled water is often toxic to a cell (Osterhout, T 3 ), producing 
pathological states similar to plasmolysis. I11 this case there may be a slight 
breaking down of the plasmatic surface; and a failure on the part of the pure 
