812 
W. L. WILLIAMS. 
ever, climate does seem to exert a powerful influence, though 
no exact data have been preserved. During 12 years’ practice 
in central Illinois in an agricultural region largely devoted to 
horse breeding and chiefly to heavy draft horses, roaring was 
rarely seen, probably one case a year was presented. In Mon¬ 
tana, in a location where there were a great many horses, three 
roarers can be recalled during a period of as many years. At 
the free clinic of the New York State Veterinary College, 25 
roarers have been presented among 3500 surgical patients. 
These figures are suggestive, but may be faulty. If true, 
they argue against heredity, for, so far as the writer can judge, 
the belief in heredity and the care exercised to prevent trans¬ 
mission is most evident where the disease is most prevalent. 
If heredity is the prevailing factor in producing roaring, it 
would seem it should appear often at birth, and the frequency 
of advent should decline with age, but not wholly cease, but in 
practice we see it occur between 3 and 6 years, and rarely out¬ 
side this range. 
Heredity should not, it seems to us, have any great prefer¬ 
ence for one sex as against another in case of a disease affecting 
an organ having comparatively slight sexual attributes, or if 
the sexuality has much to do with the heredity then the de- 
sexualization should act as a barrier against the disease. The 
25 cases entered in our clinic were as follows: Geldings, 17 ; 
mares, 5 ; stallions, 3._ 
! 
Number of cases 
which would 
result if all 
sexes were 
equally suscep¬ 
tible. 
Actual number of 
cases occurring. 
Ratio of cases 
occurring to an 
equal occur¬ 
rence without 
relation to sex. 
6000 mares. 
15 
5 
1:3 
3950 geldings. 
9- 8 75 
17 
2:1 
50 stallions. 
•125 
3 
24.1 
25- 
25 
The proportion of stallions, mares and geldings per 1000 in 
this community can only be estimated, and the following 
