96 THE MICROSCOPICAL NEWS. 
marked effect. Arguments advanced in favour of a long tube or 
of a short tube are untenable in theory; and the supposed differ- 
ences of effect have no real existence when examined under con- 
ditions which are truly comparable. ‘There will be found in every 
objective a particular angular amplification obtainable at will by 
means of length of tube and strength of ocular, which must exactly 
suffice to enable any eye possessing normal capacity of vision to 
recognize all the details that can possibly be delineated in the virtual 
image formed by the objective. And this, which may be termed 
“necessary angu/ar amplification,” may be looked upon as the mea- 
sure of the relative perfection of the objective. 
. 
(Zo be continued. ) 
NEW METHOD OF DETECTING TRICHINA: 
IN MEAT. 
YLICES, two or three millimetres in thickness, are taken from 
several different parts of the meat to be examined. ‘The pieces 
are preferably taken from the surface of the muscular portion of 
the meat. A series of thin sections are made of each of the pieces, 
and these are all plunged into a solution composed of methyl green 
I gramme, distilled water 30 grammes. After about ten minutes’ ma- 
ceration the sections are taken out, and placed to decolorize in a 
large vessel filled with distilled water. They remain there about half 
an hour, the water being agitated and changed two or three times. 
Finally, the water having become quite limpid, it is stirred up with 
a glass rod, interposing the vessel between the eye and the light, 
when the sections containing the trichinz are distinguished quite 
readily with the naked eye. The trichinze appear in the form of 
small, elongated particles, of a fine blue colour. The methyl 
green becomes fixed to the cysts of the trichinze with greater 
tenacity than to the other parts of the tissue. 
It suffices then to examine the sections with a magnification of 
fifty diameters to distinguish the worm which will be found enclosed 
in the cyst. 
If, in following this method, no trichinz are found, it is positive 
assurance that the meat is not infested with them.—4w//. de la Soc. 
Belge de Micr. 
