16 
Piper, on a Portable Slide Cabinet . 
pellets, but they simply collected in a spot agreeing with the 
position of the pellet-cup in Melicerta. There was evidently 
a viscid excretion at the spot which held the extraneous 
matters loosely together in a clot ; in about half a minute 
the rotifer would jerk down, leave the floccose deposit on the 
edge of its case, then rise immediately and repeat the process. 
On mixing a little carmine with the water, the process became 
very striking ; an irregular crimson edge to the tube was made 
under my own eyes, and, on leaving a number of specimens 
of both species in a zoophyte trough, charged with carmine, 
for forty-eight hours, I was gratified to find that a few had 
continued building, and made red tops of different sizes to 
their habitations ; nearly one fourth of the entire structure in 
two instances were composed of the mixture of the red atoms 
and gelatinous excretion. One infant rotifer, whose first 
efforts at building I had distinctly marked, seemed to have 
made his entire nest of the glowing pigment. The carmine 
apparently stimulates the creatures to activity, but certainly 
kills them in a day or two. I have mounted, in Deane’s 
gelatine, some of the red-topped cases, constructed as 
described, and I offer them as confirmatory evidence of the 
reliable character of what I advance. They tend to show, not 
only that Melicerta enjoys no monopoly in the building trade, 
but that all rotifers inhabiting opaque encrusted tubes may 
reasonably be suspected of constructing them piecemeal, and 
in the same manner. 
Finally, returning for a moment to the sheath of CE. longi- 
cornis , I would note its great internal elasticity, as shown 
especially at the aperture. It always embraces the animal, 
expanding or contracting in its movements in rising and re- 
treating, and to such an extent that when the rotifer, greatly 
alarmed, shrinks down to a mere ball at the bottom of the 
sheath, there is generally a coalescence and perfect closing 
of the orifice. 
On a Portable Slide Cabinet and a Form of Slide for 
Opaque Illumination. By Samuel Piper, Old Change 
Microscopical Society. 
(Read January 9th, 1867.) 
The Portable Horizontal Slide Cabinet is composed of any 
number of flat cardboard trays, divided into six or more 
