C. Warburton 
331 
The eggs are in this case laid singly, attached to the base of a hair. “The 
favourite places for the fly to strike seemed to be the region of the hock in 
particular, and the back of the knee, occasionally striking as high as the 
stifle (where eggs were found), and along the flanks to about the same height.” 
It was thus firmly established by direct observation that the eggs were 
never deposited by either fly on that part of the body where the warble 
tumours subsequently occurred, but before oviposition had ever been witnessed, 
indirect evidence of a very strong nature had been obtained by Carpenter and 
Steen through a series of remarkable experiments began in 1904 and published 
in 1908, and designed to test the value of preventive smearing of the backs 
of cattle, so strongly advocated by Miss Ormerod. All the usually recom¬ 
mended smears were applied in a manner much more thorough than would 
be possible with any farmer, but the cattle thus treated were no less warbled 
than the controls. The entire covering of the back with linen or calico during 
the whole fly season also failed to reduce the average number of warbles. 
The satisfactory covering of the legs was not found to be practicable, as the 
animals always succeeded in so damaging the leggings that it was impossible 
to be confident that the legs had never been exposed to the fly; nor was the 
experiment on a large enough scale to have great importance. It was found, 
however, that while four calves with their backs covered developed an average 
of 10 warbles, four others with their legs protected averaged only 3*5 warbles 
the following spring under precisely similar conditions. 
The facts of oviposition, and the knowledge which had been obtained of 
oesophageal larvae, were thought strongly to support the view that, as with 
Gastrophilus, the eggs or newly hatched larvae, were licked off by the cattle 
and that the parasite entered its host by way of the mouth. Hinrichsen 
thought so in 1888; Riley gave his adhesion to the view in 1892, and it held 
the field until 1915. 
Hatching of the eggs. 
Eggs which have hatched are easily recognised by the split distal end. 
There is no operculum as in the allied genus Oedemagena. 
Glaser observed the larva in the act of breaking open the egg-shell and 
making its exit. Approaching its mouth-hooks so that they became parallel, 
the larva alternately contracted and expanded so as to strike the anterior end 
of the shell repeatedly with the median spear till at length perforation was 
accomplished. Into the small aperture thus made it inserted the mouth-hooks, 
divaricated them, and began tearing at the substance of the shell, which 
suddenly split open when the operation had been carried on for a short time. 
The larva then crawled out by the aid of its spiny armature, especially the 
spines at its posterior end, and proceeded to make its way down the hair. 
Penetration. 
Carpenter, with the aid of various colleagues, endeavoured to test the 
licking theory by subjecting certain animals to such restraint by tying or 
