6 TRICHINA SPIRALIS. 
LIFE HISTORY OF THE TRICHINA. 
In the case of most animals, we trace the individual from its birth 
upwards, but we shall find it more convenient to begin the history 
of the trichina with the closing period of the life of its parents. 
If we find a piece of meat which has caused death, or even serious 
sickness in those who have eaten of it, we may possibly find, if this 
sickness is due to trichine, that a slice of it, when cut lengthwise 
of the fibres, has a specked appearance even to the naked eye. 
Such appearance is well represented in Figure 1, taken from’ 
Harley’s ‘‘ Histological Demonstrations.” 
In this case the trichinze have been in the flesh for some time, and 
have become surrounded with hardened (calcified) capsules, or coat- 
ings, which render their presence and position visible. But if it 
had happened that the ani- 
mal from which the meat was 
taken had become infected 
but a short time before being 
butchered, the capsules, or 
‘‘eysts,” as they are called, 
would have been transparent, 
and the parasites invisible to 
the naked eye. To detect 
them under such conditions 
we must cut a very thin slice, 
so thin as to be transparent; this slice, or, as microscopists call 
it, ‘‘section,” must be placed between two pieces of glass, and 
moistened with water, glycerine, or, better still, acetic acid. The 
plates of glass are then squeezed together, and when the piece of 
meat has become so thin that it is quite transparent, it may be 
viewed by means of a strong magnifier, by holding it up to the 
light and looking through it. Ordinary pocket magnifiers are 
not quite strong enough; one magnifying at least 25 diameters 
should be used; and then, if trichine are present, the flesh will 
present the appearance shown in Fig. 2, which has been accurately 
drawn from a piece of trichinous flesh seen under a common 
lens. 
Such a magnifying power, although abundantly strong enough for 
the detection of trichinz, is not always quite sufficient to enable us 
to make a satisfactory examination of the worms themselves, but this 
is a matter of no consequence, so far as the ordinary requirements 
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