THE CATTLE GRUBS OR OX WARBLES 51 
The occurrence of larve, varying considerably in size, on the 
surface of various abdominal organs has been noted by a number 
of investigators. For instance, Koch (53) records having found 
larvee on the pleural side of the gullet as well as under the mucous 
coats; on the surface of the spleen; some on the paunch and one 
between the muscular and mucous layers of it; a few among the 
intestines; and some in the connective tissue of the thoracic cavity 
just below the vertebral column. Horne (45) has on several oc- 
casions observed several larve in the connective tissue around the 
kidneys, and Hadwen and Fulton (40) have observed several 
larvee on the pericardium. Berg (3) has found larve in the con- 
nective tissue between the small loin muscles and the muscle of 
the hip, and Koch (43) has observed a single larva in the inter- 
muscular tissue of the back. Many writers have recorded the 
finding of larvee, sometimes in considerable numbers, in the spinal 
column throughout the greater portion of its length and also pass- 
ing through the posterior foramina. Hadwen and Bruce (38) 
state that larve observed by them in the spinal canal were found 
in the areolar tissue which surrounds the dura mater. Their 
presence was accompanied by evidences of green pigmentation and 
gelatinous infiltration at different points along the cord. . 
In the writers’ own work they have encountered larve in nearly 
all of the locations where they have been reported by others. - It is 
Pharynx 
End 
Fic. 24.—Hypoderma lineatum: Diagram showing position, direction of travel, and 
length of larve in millimeters in gullet of calf (No. 22) 
not at all uncommon for the larve to be present just under the 
pleura along the esophagus. The larvee found in that region were 
practically of the same size as those in the submucous connective 
tissue of the gullet. Wide distribution of the larvee within the ab- 
dominal cavity has been noted in the case of the experimental ani- 
mals infested at one definite period, indicating that there is a general 
scattering of the larve of the same age. On account of the interest- 
ing distribution of the larve observed in experimental calf No. 22 
the location of the larvee will be briefly summarized. This animal 
had about 300 eggs deposited upon it by flies on March 22 and 28. 
Most of these were laid in the region of the dewclaws on the hind 
legs. On July 3 the animal was killed and carefully dissected. In 
the connective tissue beneath the mucous lining of the gullet 17 
larvee were found. One of these was crushed and its position not 
noted. The position of these larvee in the gullet and direction they 
were headed are shown in Figure 24. Their size ranged from 3.6 
to 6 millimeters in length, the average being 5.3 millimeters. On 
the paunch 12 larve were found. Six of these were almost immedi- 
ately under the spleen, but none were attached to that organ when it 
was peeled off. The other six were scattered over the rumen at 
widely varying distances from the gullet entrance. These ranged in 
size from 5.8 to 8 millimeters, with an average of 6.8 millimeters. 
Some of these had the anterior end pointing toward the gullet en- 
trance, others were pointing directly away from it, and others were 
