26 Notes on some Microscopic Organisms. 
times, but perhaps thirty or forty, so that I am enabled to speak 
confidently as to the accuracy of my notes, as I have watched the 
whole process. It is as follows. At first the bright green-coloured 
cell-contents, around and investing which I have not been able to 
satisfy myself that I have seen a “ primordial utricle,” grow gradu- 
ally coarser in texture by a process of differentiation of the mass in 
such a way that granules appear which increase in dimensions at 
the expense of the surrounding and investing substance, until the 
whole cell is filled with a coarsely-granulated mass, differing little 
in colour from the original cell-contents. At the same time the 
whole green mass recedes somewhat from the enclosing cellulose 
wall, and instead of filling it completely withdraws itself in such 
a way that its outline, near the ends, becomes rounded. This 
change is by no means slow, but, when the dimensions of the 
plant are magnified by the microscope, appears to be rapid. I 
should say, although I have not timed it, that this stage occupies 
from fifteen to twenty minutes in its accomplishment. Soon 
thereafter the cell-contents contract still more, moving towards 
one end of the cylindrical cell. Then, with a sudden snap, fracture 
takes place almost entirely across the tough cell-wall at a point 
about one-twelfth of its length from one end, that is to say a portion 
measuring about one-twelfth of the length of the whole cell splits 
across with a perfectly smooth and even fracture, still adhering by 
a very small portion, and looking like the lid to a box, is thrown 
back more or less, so as to expose the transformed cell-contents to 
the surrounding fluid. Occasionally but not commonly the fracture 
extends entirely across the cell- wall, and the two resulting portions 
become separated. Usually it occurs in the way I have described, 
so that after a while, and when all the cells of a filament have thus 
opened, it becomes transformed into a chain of straight portions 
bent usually in one direction in consequence of the dehiscence occur- 
ring for the most part along one side of the filament only. But 
now the green cell-contents move towards the openings thus formed, 
and slowly and steadily push themselves outwards, and, being 
elastic, escape after the manner that a small elastic sac filled with 
semi-fluid contents would escape from the hand if pressure were 
brought steadily to bear upon it. But in this case the emergence 
is not caused by the closing in of the cell-wall, but by a motile 
power resident in the elastic sac and its contents. It is not shot 
forth suddenly from the cell cavity, but squeezes itself out, and as 
soon as it has escaped assumes the form of a perfect sphere, and, as 
if exhausted by its previous exertions, comes to a rest. But 
although the whole mass is now in motion, the cell-contents do not 
remain at rest, but go on to another change. The bright green, 
coarsely-granular sphere being at rest, is seen first to become some- 
what clearer upon the surface, and evidently a process of differen- 
