618 Price. — Some Shtdies on the Structure of the Plant Cell 
in the same way as between the gel of the nucleus and the cytoplasm, and 
if this is so, the chloroplast may be supposed to act as an osmotically 
discrete structure. 
§ 8. Some Studies of Plasmolysis. 
The phenomena revealed in the study of the plasmolysed cell by the 
dark-ground method are interesting, and certainly furnish some new ideas 
of the process of plasmolysis in general, although the interpretation of the 
structures observed is often very puzzling. Before any general discussion 
can be made, the empirical results in the best cases studied will be described. 
The ordinary appearances of plasmolysis will be assumed in most cases. 
(a) Appearance of Plasmolysed Cells in Various Cases. 
It may be noted first that Gaidukov has already described the effect 
of the entrance of electrolytes (TO) into the cell in causing the coagulation 
of the hydrosol, where it comes into contact with the protoplast, and he 
supposes that in this way a definite ‘ Plasmahaut ’ or plasmatic membrane 
may be produced on the outside. 
To study this phenomenon various types of plasmolysing agents 
and of various strengths have been used. The results are, as will be seen, 
rather various, and require very considerable amplification, but, on the 
whole, they indicate a definite formation (or previous existence) of layers 
in the protoplast on plasmolysis, and also that a differentiated surface layer 
of the protoplast exists apart from the action of electrolytes upon it. 
As plasmolysing agents, both electrolytes and non-electrolytes have 
been compared. Attempts have been made to represent roughly some of 
the more typical cases in the figures, and these will be referred to in the 
description. 
Spirogyra. 
As Spirogyra is a good object for dark-ground study, and has often 
been used for plasmolysis experiments, it was used very largely in the study 
of plasmolysis in this work. Its behaviour under plasmolysis is in some 
respects rather peculiar, and is rather variable under different conditions, so 
that various special cases will be described. 
PI. XLI, Fig. 2, represents a cell of a filament plasmolysed with dilute 
glycerine, which is to be regarded as an imperfect plasmolysing agent 
(since it enters the vacuole after a time), and also a non-electrolyte. As in 
practically every case of plasmolysis with dilute glycerine, there is what 
may be called a layering of the protoplast ; there is a distinct differentiation 
into an external layer composed of extremely fine particles only and an 
inner portion of the protoplast which contains the larger microsomes, so 
conspicuous in the unplasmolysed cell. The chloroplast is practically 
