226 General Notes. ` [ March, 
ing objects. The simple glass slip, three inches by 1 inch, or bet- 
ter, a ledged stage-plate three inches by one and a half inches, with 
narrow strip of glass cemented along one edge. One of these, 
with cover-glass, is often all the apparatus necessary to use with 
small infusoria and free-swimming rotifers, and is also occasionally 
available with a little management for larger objects, either free or 
attached. Manipulation with these I cannot better describe than 
in the words of Judge Bedwell in his ,description of what I call 
Bedwell’s rotifer-trap. 
“Take a plane glass slide, on it drop one or more of the roti- 
fers in a drop of water, about half an inch in diameter, and draw 
off the surplus water if any, carefully with the empty pipette ; then 
fray out a very, very small portion of cotton wool (I always use a 
watchmaker’s glass in the eye to do all such operations) until it is 
much extended, and spread out and lay this on the drop. Upon 
that lay the thin microscopic glass, the thinner the better, and then 
set up the capillary attraction by gently touching it with a needle. 
Draw off any superfluous water from the edges with the pocket- 
handkerchief, and. you will have a little wilderness of wool in 
in which the rotifer is restrained in its movements, protected from 
pressure, and within reach of very high powers. The amount of 
wool depends on the size of the rotifer. Hydatina requires more 
depth than Rhinops. The same plan answers equally well for all 
roving animals. The Goduride in particular, when placed in deep 
glass cells, are easily seen by this apparatus, and it saves many a 
weary and vexatious five minutes with the compressorium, which 
even at the best, requires with living animals extraordinary 
patience. The rotifers are easily found and secured with the 
pipette and a watchmaker's glass in the eye after a very little prac- 
tice. Mr. Bolton’s studio is of the greatest value to naturalists, 
and cannot be too well known, for to those who have not time to 
look for specimens it is a great privilege to be able to purchase 
them.” 
Another simple apparatus I call the Wills’ compressorium. 
Most forms of compressorium are useless—all are expensive. 
Those who try the following will be surprised at the efficiency of 
the apparatus. Two pieces of thin glass are cemented on toa 
glass slip in the shape of the letter L, but with the two strokes of | 
the letter about equal in length, and another thinner and longer 
one is fixed longitudinally, thus . The L serves to retain in 
position a square slip of cover glass placed, of course, not on the 
L, but inside it; the horizontal piece, which should be ground toa 
bevel on its top edge before fixing it, serves to carry a fine needle, 
the point of which is inserted beneath the edge of the cover glass. — 
This point being tapered, it is easy to increase or diminish the 
thickness of a film of water carried between the cover and the o 
slip by pushing the needle further in or out, and so to forma — 
cheap and effective compressorium.— T. Boltonin English Mechant. 
