1901} -MICROSCOPICAL JOURNAL 229 
is large enough for the blow-fly, but can be made of any 
size. It consists of a brass cone soldered to a brass 
plate with a hole in it, just large enough to admit the 
head of a fly, which is surrounded by a disc of ivory set 
into the plate. The fly is gently pushed into the cone 
with. a little piece of wool behind it, and is ready for 
examination. A little treacle or honey is put on to the 
ivory disc; the fly puts out its proboscis, which is kept 
flat and in one position. It is very easy to focus, and 
requires no more adjustment of the object than an ordi- 
nary slide. 
MiTEs IN Microscopic Siipz.—lI have aslide ofa por- 
tion of the polypary of a Californian zoophyte (Membrani- 
pora tuberculata) mounted as an opaque object for top- 
light. It is ina cell which is securely sealed by an or- 
namental paper with an opening to show the object, but 
otherwise covering the 3x1 glass slide thoroughly and 
effectually, the object being hermetically sealed. I have 
no record of the preparer, except that it is not my own 
work. The slide has been in my cabinet for certainly 
not less than ten years, and, until] a day or two since, for 
a very long timeI have not seen it under the microscope. 
On this occasion I had it under the 2-inch and brilliantly 
lighted by the side-reflector, when some moving object 
in the cell caught my attention. This moving, living 
object proved to be a mite, whicb was active and vigor- 
ous, and, so far as I could examine it, resembled, the 
cheesemite (Tyroglyphus domesticus). It was not alone, 
for I quickly discovered another, equally lively, and on 
looking closely I found two exuviae and what looked 
like portions of others. The object in which these mites 
have been carrying on their life-histories is about 3-10th 
of an inch square, and presents on the surface 360 thecae, 
or cells—a sufficiently big world for two or three or- 
ganisms so tiny—but whence came they, and whence 
