14 ; TRICHINA SPIRALIS. ss 
These facts, combined with the extraordinary fecundity of the 
trichine themselves, readily explain the occurrence of epidemics of - 
trichiniasis. Indeed, when we consider the very small number of 
encysted trichinz, which, after passing through two or three animals, 
may give rise to a brood of many millions of embryos, the wonder is 
that, under our present system, trichinosis is not a more common 
disease than it is. 
Let us suppose that a rat, feeding on the offal of a slaughter 
house, picks up two dozen trichine in a piece of meat—a very 
small number. Cobbold, one of the most thorough and careful 
authorities, in his calculations, claims for each trichina an average 
progeny of about 3,000.* We will take, therefore, half this number, 
and assume that after the regular time our rat has 36,000 encysted © 
trichine in its muscles. If, now, this rat be eaten by a pig, the 
latter animal will become the host of 54,000,000 trichinz, and its 
flesh, in quantities of half a pound or so, would be fatal to any 
human being that might eat it without having it properly cooked. 
DESTRUCTION OF TRICHINA. 
We have already stated that the trichina is exceedingly tenacious 
of life, resisting the effect of powerful chemical agents, and the de- 
stroying influence of putrefaction in the meat in which it is em- 
bedded. Cobbold fed a dog with a small piece of trichinous human 
flesh which had been saturated with a solution of chloride of zine, 
and afterwards, on killing the animal, he found it infested with 
trichine. Indeed, the trichine were seen to be alive in the 
flesh before it was fed to the dog. Ordinary salting and smoking 
do not destroy this parasite, though long-continued exposure to 
smoke does kill them. It has been found that some chemical agents 
cause their speedy death, but we do not regard such methods of de- 
struction as of any great value. 
Fortunately, we have, in the simple process of thorough cooking, 
a perfectly efficient means of killing trichine and all other parasites. 
But in order to be effectual, the cooking must be thorough; no mere 
surface scorching on the one hand, or brief dipping in boiling water 
on the other. It has long been known that a lump of flesh, placed 
in boiling water, may be very thoroughly cooked: on the outside, 
while the interior has not reached a temperature high enough to 
*This estimate makes allowance for the fact that half of the trichinz 
are males, and also for the loss incurred by the expulsion of embryos 
and mature females with the feces. 
