TRICHINA SPIRALIS. ii 
ditions, it is necessary to examine the means by which trichinz are 
transferred from one animal to another. ‘These are: 
1. By eating trichinous meat. 
This is by far the most common method, and is, undoubtedly, the 
way in which pigs and rats generally become infected. And as it 
happens that the parts which are generally thrown aside as offal 
(the diaphragm, the head, and the parts at which muscles and ten- 
dons join), are those which are specially liable to contain trichinx, 
it follows that the pigs which are reared on offal, and the rats which 
infect slaughter houses, are very liable to contain trichine. 
2. By eating the excrements of animals that have recently been infected 
with trichine. 
- The dog, the pig and the rat are all ravenously fond of excremen- 
titious matter—eating it greedily, when they can getatit. Now, when 
an animal has recently had a dose of trichinous flesh, there will 
always be found in the feces, not only young trichine, but mature 
females which have not yet got rid of their burden of young. 
When taken into the stomach of another animal, these young tri- 
chinz develop and bore their way through the intestines and muscles 
of their new host, and the females complete their functions in their 
new abode. Hence it is a well-known fact that one trichinous hog 
will infect a whole herd, and it was, doubtless, from the excrements 
of rats, mingled with its food and water, that the hippopotamus in 
the Zoological Gardens of London, obtained the trichine which 
were found to infest its muscles. 
3. By drinking water in which trichinous flesh has putrefied or decom- 
posed. 
One of the most remakable characteristics of the trichina is its 
power to resist the action of agents, which are destructive to most 
other animals. The gastric juices of the stomach, the influence of 
putrefaction, and even soaking in strong chemicals, such as chloride 
of zine, all fail to destroyit. The Vienna Committee reported that 
‘‘after remaining for months in putrefied flesh, they (trichinz) did 
not lose their vitality.” And Goujon succeeded in infecting with 
trichinous meat 80 to 100 days after it became putrid. The obvious 
result of this is that if a trichinous rat, cat, dog, or pig should die 
by the side of a stream, or be drowned in it, and the flesh should 
putrefy, any animal that drinks of the water in the immediate 
neighborhood may pick up quite a number of trichinz, and these, 
when introduced into the stomach, will soon be multiplied by 
thousands. In this way oxen and horses, though strictly herbi- 
