| Mes. CORP. 2851, | 
L133 32" 
PERICHINA SPIRALIS. 
(Pork-worm or Flesh-worm.) 
THERE is probably no country in which the Pig serves a more 
important purpose than in the United States. The ease with which 
the animal is raised; the facility which it affords for converting 
corn, clover, and similar bulky articles into a concentrated form of 
food, and the ease with which its flesh is cured for storage and 
transportation, all combine to render it a source of immense income 
to the country. Consequently, anything which tends to injure it as 
a food product, lessens the amount produced, interferes with the 
market for it, and thus becomes a great national evil, as well asa 
source of disease and death to thousands. 
That the Trichina spiralis, or, as it is sometimes called, the ‘‘ pork 
worm” or ‘flesh worm,” does decrease the market value of the 
‘hog crop,” is a fact too well known to require elaborate proof at 
our hands. Of the many undoubted cases of trichinosis which have 
occurred in this country, several have been caused by native pork, 
and the elaborate investigations of Dr. Belfield and Mr. Attwood 
showed that during a certain period the astonishing amount of 
8 per cent. of the hogs slaughtered in Chicago were infested w*th 
this parasite! And so deeply has this been impressed upon foreign. 
governments, that in many European countries the importation of 
American pork is permitted only under the most stringent regula- 
tions. These facts show the importance of a general diffusion of in- 
formation in regard to the best means that have been discovered for 
detecting this pest where it exists, and o: avoiding lts effects, as well 
as of preventing its increase, 1f not of stamping it out altogether. 
To do this, however, it will be necessary, first of all, to give a brief 
account of what is called the ‘‘life history ’ of the parasite—that is 
to say, of its changes and modes of growth, from its first appearance 
as an embryo, to the death which overtakes 1t when it has finished its 
career according to natural laws. : ge 
