THE CONTAGIOUS DISEASES (ANIMALS) ACT, 1869. 419 
The number of larvae found in examining the sinuses has 
often exceeded a score. Doubtless others have escaped, so 
that we are without positive information as to how many may 
originally have been present. 
The inhalation of the fumes of burning tar, especially if 
made more potent by casting on the flame small quantities of 
sulphur from time to time, has proved useful to those sheep 
which gave early indications of being affected, by causing a 
more speedy expulsion of the larvae. The exhibition also of 
a little turpentine mixed with glycerine has led to a similar 
result. 
It seems almost unnecessary to add to these remarks by 
further reference to the natural history of the ^Estrus ovis. It 
may, however, be stated that in the latter months of the summer 
the fly deposits its ova near to the nasal openings, notwith- 
standing the efforts which are made by the sheep to guard 
against this being done by herding themselves as close together 
as possible, and keeping their muzzles almost buried in the dust. 
Within a few days the young larvae, scarcely visible to the eye, 
are hatched, and immediately they begin to crawl into the nasal 
passages, and to feed upon the natural secretion furnished by 
the mucous membrane. They march onwards into the 
frontal and other sinuses, where, as their proper habitat, they 
remain until about the beginning of the month of May, or a 
little later, by which time they will have attained their full 
development. The change they are now about to undergo, 
viz. the pupa state, leads to their efforts to escape, and which, 
as has been shown, may be attended with serious con- 
sequences to the sheep. When free from their dwelling place 
they bury themselves just beneath the surface of the soil, and 
are soon transformed into their perfect chrysalis form. After 
a few weeks — sometimes five or six, but varying according to 
circumstances — the fully formed sestrus bursts from its prison 
house, seeks its mate, and in due course the impregnated 
female deposits her ova on the part of the sheep already de- 
scribed. Climatic variations greatly influence the perfecting 
of the transformations of the larvse. In cold seasons they 
perish in considerable numbers, while in hot they are pre- 
served, and hence in such years as 1868 and ’70 myriads of 
sestri were perfected which otherwise would not have been. 
THE CONTAGIOUS DISEASES (ANIMALS) ACT, 1869. 
“Return of the Number of Foreign Animals brought 
by Sea to Ports in Great Britain, which on inspection on 
landing, within the Month of April, 1871, have been 
