122 STATE BOARD OF HEALTH. [Jan. 



An inspection of the above tables shows that, of the 3,064 

 hogs raised near Boston, 394, or 12.86 per cent., were 

 trichinous ; and that, for the several years over which the 

 examinations extended, the lowest per cent, of infection was 

 9.6, the highest 16.26. 



As regards the sex of the hogs, there were nearly twice 

 as many females (1,961) as males (1,103) examined. The 

 degree of infection among females was 14.07 per cent., while 

 in the males it was only 10.61 per cent. It is noticeable 

 that there was greater fluctuation from year to year among 

 the males (20.95 per cent, maximum; 6.61 per cent, mini- 

 mum) than among the females. The per cent, with the 

 latter never fell much below 12. I know of no grounds 

 upon which the comparative immunity of the males from 

 infection can be explained. 



Only 234 hogs slaughtered by State institutions have 

 been examined, but of these, 42, or 17.95 per cent., were 

 trichinous. Over half of these were received from one in- 

 stitution, where specially dangerous conditions were dis- 

 covered, which may serve to explain in part the high degree 

 of infection. This case will be considered farther on. The 

 combination of these two tables of results gives, as the total 

 number of hogs examined from Massachusetts, 3,298, of 

 which 436, or 13.22 per cent., were trichinous. Besides 

 these, I have examined from all other sources — principally 

 Western, and including the 500 reported on in 1881 — 888 

 hogs, of which 21, or 2.36 per cent., were trichinous. 



Table III. gives the results of examinations in fifty-six 

 cases, tabulated by years. They embrace all the cases of 

 hogs raised near Boston in which as many as fifteen hogs 

 from the same source have been secured for examination. 

 The number before the colon shows the number of hogs 

 examined ; that after the colon, the number found to be 

 trichinous. Table TV. gives similar statistics from eight 

 State institutions. 



In Table V.* is given the number of encapsuled worms 

 found in each of the 436 cases discovered in hogs raised 

 near Boston or in State institutions. The amount of muscle 

 examined was subject to some variation, so that the figures 



* A dagger (f) following a number indicates that the parasites were dead. 



