622 Price. — Some Studies on the Structure of the Plant Cell 
workers have observed only the coarser threads (de Vries, ’ 85 ) which are 
generally present, but the difference is not very material, being probably 
one of size only. 
Observations of them have been made in most cases, but they have 
been studied more especially in Spirogyra, Mougeotia , E lode a, Cucurbit a ^ 
Vaucheria. Plasmolysis, usually for a short period (10-15 minutes) in the 
agents and of the strengths described, generally produces the fibrils, and 
after a little experimentation they can be produced almost with certainty 
in any given material. 
The fibrils are often very distinct and numerous in Spirogyra. They 
appear sometimes quite straight as though stretched, but more often 
branched towards the wall and loose. Under these conditions the threads 
are seen to have a constant and fairly rapid waving motion, as though 
swayed by a gusty breeze (cf. Hecht, T 2 ). This movement of the fibrils 
is possibly to be attributed to the Brownian movement of the cell contents ; 
it may be impressed on the fibrils by the oscillations of the particles of the 
protoplast at the base. It may, however, be a manifestation of direct 
molecular movement, the same phenomenon as the Brownian movement 
manifested in these fine fibrils. The idea that the fibrils are moved by 
diffusion or by osmotic currents is hardly feasible on account of the rapidity 
and oscillating nature of the motion. 
The fibrils themselves seem to be homogeneous in structure, but often 
carry particles in their substance which are identical with the protoplasmic 
particles ; they are often much finer than the diameter of the larger proto- 
plasmic microsomes. The particles seem to show some movement of 
translation of their own, and their presence may in some cases help to 
produce the Brownian oscillation of the whole fibril. Ultimately the fibrils 
often break, and their free ends can be seen waving in the liquid, and they 
are often so numerous as to give a distinctly cloudy appearance to the space 
between the cell-wall and protoplast. In this way also it seems that 
particles may be liberated from these fibrils into the liquid. 
In some cases the fibrils appeared very clearly as though pulled out 
from the outer layer of the protoplast (PI. XLI, Fig. 2), which contains the 
finer particles. In some cases also, little attaching discs of protoplasm 
appeared on the cellulose wall of the cell. In one case especially of 
plasmolysis with glycerine, very numerous threads were produced. These 
could be seen to pass to a wall which lay slightly obliquely with the vertical 
plane. A little patch or disc of protoplasm, composed of very fine particles in 
rapid motion, was present here at the end of one of the fibrils (PI. XLI, Fig. 2), 
and pulled out into a little V~ s h a P e d piece as though slightly viscous. Such 
protoplasmic discs seem to correspond to the protoplasmic network on the 
cell-wall described recently by Hecht (T 2 ). It seems possible that such a disc 
may really represent the end of a protoplasmic connexion passing through the 
