184 THE NORTHERN MICROSCOPIST. 
and fully verified, are copied from notes made in the Summer of 
1879, and are a contribution to the record of facts which any 
sound theory on the subject must account for. They certainly 
seem most consistent with a supposition of ciliary action, though 
it is possible that some form of osmotic action might produce simi- 
lar phenomena. 
A fresh gathering of diatoms from a little brook near Cincinnati, 
contained a number of JVitzschia linearis, which had progressed so 
far in self-division that the front view of the frustule was twice as 
broad as the side view, but from the peculiar form of the JVitzschia 
the carina was in plain view on each edge of the frustule as it lay 
or moved on its broader side. The first case I noticed was that of 
a frustule apparently held fast by the glasses of the compressor, 
but a gelatinous mass of decomposed vegetable matter was seen 
moving steadily along the frustules from one end to the other, 
making a momentary halt in the middle. The mass was as large 
in diameter as the width of the diatom, so that it reached from 
side to side of the frustule, overlapping the carina of the valve on 
one side. The motion of the loose matter was once or twice re- 
versed, as if the diatom was trying to back out of its position, and so 
produced a current in the opposite direction. Presently the diatom 
got loose, backed out and moved a considerable distance across 
the field, the gelatinous substance still adhering and being dragged 
after it. Again an obstruction was met, the diatom stopped, and 
as if the machine were reversed in the new effort to back out, the 
foreign matter was again dragged to the foremost end, and this 
time a smaller floating particle of similar kind moved in the same 
manner along the opposite valve of the frustule. In an effort to 
make the diatom roll over, so as to enable me to make more sure 
of its species, it was swept out of sight and lost. 
A little later some fresh samples of similar materials afforded a 
repetition of the phenomena and a confirmation of the facts. A 
frustule of the same species as the former was so wedged in the 
compressor that one end was free, whilst the other was fast. ‘The 
free end would move vigorously one way or the other, in an arc of 
a circle, but the diatom was not released. Attached to it were two 
gelatinous masses, one on each side, and of similar size to those 
described in the former case. These were distinctly applied to the 
valves so that, as the diatom lay in front view, as before, the two 
masses were on the opposite sides of the frustule. ‘These masses 
moved along the sides, sometimes the whole length of the diatom, 
sometimes only to the middle, where they would rest a while, and 
then either complete the motion or go back. They did not always 
moye simultaneously, nor with the same speed, but with a general 
agreement of motion. The action was continued half an hour, the 
diatom not getting free. 
