GASTROPHILUS HAEMORRHOIDALIS AND OTHER BOTS. 29 
Upon the suckling colt the first egg disappeared upon the ninth 
day; the eleventh day, two; the thirteenth, five; and the fourteenth, 
six. Five other eggs about 1 inch from the mucous membrane and 
upon the dry portions yielded dead larve when examined. 
Upon the lips of the cripple horse and within 1 inch of the mucous 
membrane 15 eggs were deposited. The first 6 eggs disappeared 
upon the seventh day from near the corners of the mouth. The last 
egg disappeared upon the eighteenth day. 
The normal horse in grazing received 14 eggs within 1 inch from 
the mucous membrane. Upon the sixth day 10 eggs disappeared 
from near the corners of the mouth, which was probably five days 
from deposition. The other 4 disappeared during the following 
three days. 
The striking feature of the above three cases is that those eggs 
deposited where they received most moisture and friction were the 
first to disappear. Prior to disappearance, the color changes, being 
first brownish, then a brownish red, finally with a whitish tip, thus 
clearly indicating embryonic development. It is also clearly seen 
that the amount of grazing affects the incubation, as the normal 
horse grazed practically the whole time, the cripple only at times, 
while the suckling colt was not observed to graze. There were no 
indications that the larve burrowed into the lips, and as well-incu- 
bated eggs have produced larve under moisture and friction when 
removed, it is certain that the method of ingress of larve into the 
host is not unlike that of G. intestinalis. It is true that eggshells 
were never found attached to the hairs after the larve had emerged, 
but it is believed the moisture and friction are sufficient to remove 
these after the larve leave the eggs and enter with the food. 
Incubation records are not confined to the above three cases. 
Upon August 24, 1915, one other animal was freed of eggs and 
allowed to receive depositions during 24 hours. Upon the moist 
portions of the lips 17 eggs were found, while 6 were deposited 
upon the dry portions 1 inch from the mucous membranes. Separate 
notes give a comparative idea of the incubation. Upon the sixth 
day, probably 5 days from deposition, 4 eggs disappeared from the 
moist portions and others disappeared the following day. Upon 
the dry portions all were present upon the twelfth day. Three of 
these when removed contained dead forms and the other 3 disap- 
peared from the eighteenth to the twenty-third day. 
The day of oviposition in the above cases was favorably followed 
by three cloudy days, which prevented other ovipositions. The de- 
velopment of the embryo in eggs upon moist portions was quite in 
contrast to those upon the dry portions, showing clearly the necessity 
of moisture and friction. Such observations indicated that those 
