607 
by the Method of Dark-ground 1 llumination. 
The nucleus has been observed in some cases in the living cell, a descrip- 
tion of this being given below. No very definite membrane bounding the 
vacuole could be made out in this case, nothing more than would be expected 
from the appearance of the surface of a viscous fluid. 
The vacuole itself contains numerous 4 sap particles which are 
undoubtedly of two kinds and which vary in number with the vitality of 
the cell. In some cases these particles aggregate together and form a mass, 
which lies in the vacuole and is slowly rolled about by the circulating 
protoplasm. No account of any observations on such a body could be 
found. Generally, the sap particles have a Brownian movement quite 
independent of the protoplasmic movement, though at times some of the 
particles become attached for a time to the protoplasmic stream, and are 
carried along as though adhering to a viscous surface. This independence of 
motion is perhaps one of the best tests of the identity of the sap particles. 
E lode a densa. 
The leaf-edge cells of this species are rather larger than those of 
E. canadensis and provide good material. The phenomena shown are much 
the same as for E. canadensis. The sap particles are very distinct and of 
a crystalline character, clearly seen in direct illumination. As, however, 
the material is more difficult to obtain and keep healthy, it was not used 
extensively. 
Saprolegnia. 
Many fungal hyphae seemed to promise good material for observation. 
The rather large coenocytic hyphae of Saprolegnia are quite suitable and 
revealed some interesting features. 
In many cases a most active oscillating movement of the protoplasmic 
particles occurs, but in certain regions 4 plugs ’ are present in the hyphae, 
with bright particles and no apparent motion, while in the case of older 
material very little movement of particles was made out. 
At the ends of the hyphae, the protoplasm is generally densely packed, 
and it is to be expected that here the greatest activity of the protoplasm 
would be manifested. In some cases, no motion at all could be observed, 
but in others a very rapid movement as of very fine closely aggregated 
particles was clearly seen. The appearance of fixity may of course be 
elusive, as Gaidukov has pointed out, but there is here no direct evidence 
for the presence of amicrons ; in fact, the appearance of closely packed 
particles rather controverts this. 
In the clearer parts of the hyphae — for example, below a sporangium, 
or between the protoplasmic plugs — larger vesicular 4 particles ’ are usually 
clearly seen, with an oscillating and wandering motion. These are clearly 
visible in direct illumination, but there is considerable difference in size, so 
