2 BULLETIN 880, U. S. DEPARTMENT OF AGRICULTURE. 
pork products of kinds that are usually cooked before eating, but 
that the manufacturer is under obligations to make sure that pork 
products sold as cooked products are properly cooked or, if of a kind 
customarily eaten without cooking, to make sure that the products 
are free from viable trichine. In the Federal meat-inspection regu- _ 
lations it is therefore provided that products that are cooked in estab- 
lishments under inspection must be cooked in accordance with methods 
approved by the chief of the Bureau of Animal Industry, and further 
that products containing any raw muscle tissue of pork, if of a kind 
prepared customarily to be eaten uncooked, must either be subjected 
to sufficient heat to destroy the vitality of any trichine or be sub- 
jected to other processes sufficient to destroy the vitality of trichine. 
The questions of the destruction of the vitality of trichine by 
refrigeration and by heat have been discussed in other papers (Ran- 
som, 1916; Ransom and Schwartz, 1919). It is the purpose of the 
present paper to record the results of investigations relative to the 
effects upon the vitality of trichine of various methods of preparing 
pork products of kinds customarily eaten without cooking. Though 
these results have not heretofore been published in detail, they have al- 
ready been utilized in the formulation of methods for the preparation 
of pork products of kinds customarily eaten without cooking. Such 
products may be prepared in establishments operating under Federal 
inspection only in accordance with approved methods. Details of 
these methods are given in Service and Regulatory Announcements 
of the Bureau of Animal Industry No. 128, December, 1917, page 
131; No. 135, June, 1918, page 54; No. 143, March, 1919, page 19, 
and No. 151, November, 1919, page 121. 
REVIEW OF THE WORK OF OTHER INVESTIGATORS. 
In the extensive literature on trichine the effects of salting and 
smoking upon the encysted parasites are frequently referred to, but 
only a few investigators have actually carried on experimental work, 
most of the references in the literature consisting of repetitions of 
the statements made by these investigators. In addition to state- 
ments based on the results of experimental work, other statements 
are commonly made that have no apparent basis except the opin- 
ions of the writers that made them, or of other writers whom they 
have quoted, and these are often more or less at variance with the 
facts. The important contributions to our knowledge of the effects 
of curing processes upon trichine so far as heretofore published may 
be covered in a comparatively brief summary. 
Haubner, Leisering, and Kiichenmeister (1863) concluded that 24 
hours of hot smoking rendered sausage made of trichinous pork 
innocuous, since two rabbits to which the sausage was fed did not 
become infected. These investigators also found that cold smoking 
