LIVESTOCK PARASITOLOGY — SCHWARTZ 351 



step that resulted in placing a stigma on pork produced in this coun- 

 try — a stigma which has persisted for many decades. By 1881 restric- 

 tive measures against the importation of pork from the United States 

 were promulgated by various governments of continental Europe — 

 Italy, Austria, Germany, and France following one another in rapid 

 succession. In the year before this prohibition went into effect, 70 

 million pounds of pork from the United States had been exported to 

 France, and 43 million pounds to Germany. For the next 10 years 

 pork from the United States was shut out by governmental decree 

 from nearly every market on the Continent of Europe. To regain 

 this export trade, there was inaugurated in 1892 a system of micro- 

 scopic inspection of all pork intended for export. This inspection, 

 which was terminated in 1906, was carried out only to meet the 

 requirements of the import countries, some of which required a similar 

 inspection under their own meat hygiene practices. Under current 

 Federal meat inspection there is no provision for microscopic inspec- 

 tion of pork intended for any purpose whatsoever. The abandonment 

 of microscopic inspection of pork for export resulted from reports, 

 especially from Germany, that trichinae were found from time to time 

 in pork that had been imported from the United States and certified 

 as free of these parasites. This was not surprising, considering the 

 fact that it was well known in countries that had had experience with 

 this scheme of prophylaxis that the detection of trichinae by micro- 

 scopic inspection is, at best, a hit-or-miss method. The parasites 

 were not discovered, as a rule, in lightly infested carcasses and were 

 overlooked at times even in those that harbored sizable infections. 

 Studies made in this country before 1891 showed that only about 2 

 percent of the hogs were infected with trichinae. The routine micro- 

 scopic inspections of pork (pi. 1, fig. 2), that were made over a period 

 of years thereafter showed that in over 8,000,000 hogs from which 

 muscle tissue was examined microscopically, live trichinae were found 

 in only about 1.5 percent. Studies made a decade or so ago by the Bu- 

 reau of Animal Industry by the far more accurate digestion technique 

 (pi. 1, fig. 3), also showed an over-all infection rate of about 1.5 per- 

 cent. When critically analyzed, however, the newer figures actually 

 showed that in the intervening years there occurred a sharp reduction 

 in the prevalence of trichinae in swine, especially in those raised on the 

 farm. In one series of examinations, involving both microscopic in- 

 spection and digestion, it was found that in only 21 percent of the dia- 

 phragms in which trichinae were discovered by the digestion technique 

 could these parasites be demonstrated by microscopic inspection. Dur- 

 ing the past 2 years, trichinae in very small numbers were found in our 

 laboratory by the digestion technique in about 1 percent of about 1,200 



