668 
Trichina and their Distribution. [November, 
turned over pastures or market-gardens, as at Gennevilliers. 
It is perfectly possible that man and herbivorous animals 
may in this manner receive the infection. 
It is interesting to notice the very illogical manner in 
which irrigationists have sought to disprove the danger of 
the transfer of Trichina , and of Entozoa in general, through 
the agency of their favourite scheme. They have, forsooth, 
fattened an ox upon sewage-grown vegetables, and have then 
submitted the carcase for microscopic examination to com- 
petent authorities ; and no signs of the presence of internal 
parasites having been discovered, they have ventured to pro- 
claim the danger entirely imaginary ! But no one has as- 
serted that every sewage-irrigation field must at all times 
receive Entozoa or their germs, and that every animal fed 
upon the produce of such fields must be infedted. There is 
merely the great probability that such may be occasionally 
the case, and in virtue of the very serious character of the 
consequences our only safe course is to treat all sewage- 
grown vegetables, and all animals fed upon such vegetables, 
as suspicious. A man adopting the irrigationist logic might 
say “ I have eaten a slice of raw ham, or a raw sausage, or 
an underdone pork-chop, and have suffered no injury : there- 
fore Trichina , if they exist at all, are harmless ! ” So long 
as we know that Entozoa can, and actually do, exist in 
sewage, so long we are warranted in protesting against its 
diredt application to crops which are to be eaten in an un- 
cooked state, either by man or beast. 
It must of course be admitted that the number of Tri- 
china which may be introduced into an ox by a draught of 
infedled water or a feed upon contaminated grass, clover, or 
cabbages, or into a man through the medium of a salad or 
a stick of celery, is very small. But unhappily the pest is 
rapidly prolific. Each female brings forth about 10,000 
young, and if we assume that half the adult Trichina are 
males, and that a considerable proportion are expelled from 
the body of their host, along with the excrements, before 
they have time to bore their way through his stomach and 
bowels and enter his muscles, we may assume, with Dr. 
Cobbold, an average progeny of 3000 for each Trichina 
swallowed. Phin, for argument’s sake, takes only half this 
number, and calculates accordingly that if a rat, feeding on 
butchers’ offal, swallows two dozen Trichina , it will shortly 
have 36,000 of their progeny encysted in its muscles. Suppose 
the rat to be in due course devoured by a porker, the latter 
will speedily contain a population of some fifty millions, and 
its flesh, if eaten by human beings in doses of (say) half a 
