305 
the present time. Itwill be remembered that in the summary of the life- 
history of the better known Ox Warble, viz, Hypoderma bovis (INSECT 
LiFE, Vol. 11, pp. 172-177), the actual mode of oviposition was shown 
to be not absolutely known, and that between the two opposing views 
that were held, viz, insertion of the egg in the skin, or its attachment 
to the skin or to the hair, a number of reasons based on recollection, on 
the structure of the ovipositor and on the structure of the egg, were 
urged in favor of attachment rather than of insertion. From the strue- 
ture of the egg Dr. Curtice also drew the conclusion that the egg is at- 
tached to the hair of the animal, but from the other facts observed by 
him he also concluded that the young larve are licked off by the cattle, 
swallowed or lodged in the back of the mouth or esophagus, and pene- 
trate the esophageal walls. These conclusions were deduced from the 
presence of the young grubs in the esophageal walls in November, and 
long before they are found in the backs of the cattle. Later, about 
Christmas time, they appear suddenly in full force under the skin of 
the back. The earliest larve occurring beneath the skin differ in no 
wise from those found in the esophagus. By the latter part of January 
or the beginning of February all have disappeared from the esophagus, 
together with all traces of the inflammatory action in that organ so notice- 
able in January. The larve at this stage are able to pierce through the 
esophagus and wander through the tissues to the back. The wander- 
ing of the larvee is further shown, according to Dr. Curtice, by the fact 
that they have been found near the eleventh rib on the thoracic side, 
also in the spinal column, in the subcutaneous muscles, and connective 
tissue. Dr. Curtice has also found in the esophageal muscular coats 
wounds which he believes to have been caused by the larve in pene- 
trating them. He has also found on the inside of freshly removed hides, 
which carried larve in the first or cutaneous stage, small gnawed spots 
which he believes to have been made by these larve. He says also: 
The earliest grub holes that I have been able to find are very uniform in size, cor- 
responding with the caliber of the grubs contained in them, and had no appearance 
of the sac which forms later. The walls were rough, as if gnawed, and the hole was 
cylindrical to near the epidermis, when it suddenly contracted. Now the freshness 
of the wound and the absence of inflammatory action is a very good index of the 
lateness of the wound, for, when a wound is exposed to the air, germs are sure to 
enter, a sac grows and secretes pus. Were the wound of a more remote date it 
would be quite of another character, as every pathologist will admit. 
Upon this theory Dr. Curtice explains the “lick” as nothing more 
than an effusion of serum into the connective tissue caused by the 
inflammation induced by the wandering of the young grubs, and it 
appears also in the walls of the esophagus just before the disappear- 
ance of the grubs therefrom. These licks disappear from beneath the 
hide when the grubs become stationary and the “ sacs” are well formed. 
On reaching a suitable point in the back the warbles are supposed to 
bore through the skin, caudal end first; this end being provided in 
this stage with numerous rows of short stout spines (Figs. 48d and 49¢). 
24164—No. 9 2 
