6 BULLETIN 100, V. S. DEPARTMENT OF AGRICULTURE. 
hard to the touch and contain no fluid. Encircling the base of each 
nodule there usually appears a pale or bright vascular area, appar- 
ently due to increased vascularity (which a histological examination 
proves correct), thus giving the lesion the appearance of a minute 
vesicle surrounded by a vascular girdle. The nodules are scattered 
here and there, frequently along the floor of the vulva in the clitoral 
region, but quite as often on the sides or the roof of the vulva. Except 
for the nodules and the vascular girdle about the base of each, the 
surface of the mucosa in the early stage is smooth, pale rose-colored, 
and normal. There is no swelling, no inflammation, no discoloration 
of the vulvar mucosa, and no mucous or muco-purulent discharge. 
Slowly and insidiously the disease spreads to individuals which 
have hitherto escaped, so that the older the heifers in a herd the 
larger the percentage which shows the evidences of the disease. 
The rapidity and uniformity in the spread of the malady rests largely 
upon environment. In the closely housed and much-handled heifer 
calves in dairies usually more than 90 per cent show the disease at 
4 months of age, and before they reach one year the visible infection 
generally reaches 100 per cent, but if by any chance an individual 
escapes infection until breeding age the first service by the bull 
conveys the disease. In heifer calves not kept in close or prolonged 
contact with their dams or with older infected heifers, and not much 
if at all handled by persons who are habitually in contact with dis- 
eased a nim als, the infection spreads much more slowly. Thus we 
have observed in a herd of pedigreed Herefords approximately but 
50 per cent of infection in virgin heifers and heifer calves. After 
birth these calves were allowed to go with their dams for a day or 
two and were then permitted to suck twice daily, but otherwise were 
kept separate from their dams or other older cattle. 
In experimental heifer calves we have kept individuals up to 6 
months, and even to one year old, without any trace of the infection. 
The influence of environment upon the spread of the infection in 
heifer calves is further exemplified by Table 1, wherein the 122 veal 
heifers observed showed an average infection of 61 per cent. The 
percentage of infection among these calves is markedly below the 
average infection among heifer calves in eastern dairy herds of corre- 
sponding ages. Western veal calves largely run at liberty in the 
open, exposed to the infection from their dams but not from personal 
handling or close crowding in stables. 
The number of the nodules generally increases slowly with the age 
of the virgin heifer from the date of infection up to puberty or 
estrum, when the increased vascularity and functional activity of 
the genital tract apparently favors a more rapid multiplication of 
the nodules and intensifies generally the symptoms of the malady, 
but these in the virgin heifer rarely if ever attain that intensity 
commonly seen after copulation. 
