﻿52 BULLETIN 1369, IT. S. DEPARTMENT OF AGRICULTURE 



pointing in various directions. Some of those closest to tlie gullet 

 entrance were headed toward it. A number were along* the line 

 of attachment of the first and second stomachs. On the surface 

 of the second stomach a single larya, 7 millimeters long, was found. 

 On the surface of the colon, about 15 inches from the anus, one larva, 

 7 millimeters long, was taken headed forward. Seven larvse were 

 taken in various places in the mesentery of the small intestines. Six 

 of these were 7 millimeters and the other 6.8 millimeters long. One 

 larva, 6.1 millimeters long, was found on the surface of the sixth 

 rib, just imder the pleura, about half way between the sternum and 

 the vertebra. This larva was headed ventrally and was rather 

 slender. One larva, 6 millimeters long, was found free on the basal 

 portion of the twelfth rib after the muscular tissue had been stripped 

 off. A careful examination of the other internal organs, diaphragm, 

 muscular tissues of the back, and muscles of the legs was made with- 

 out finding any indication of the presence of larvae. 



It is noteworthy that the larvse in the gullet averaged smaller 

 than those in the paunch or elsewhere in the abdomen. This of itself 

 might suggest that the older larvae were passing backward from the 

 gullet to the paunch or elsew^here. When consideration is given to 

 the fact that larvse much larger than these are found in considerable 







A 

















- 



-* 



~*_^ *< ^ 





B 



Pharynx 

 tnd 





" - 



^ 



j-^ :j 



_E^ -- ^^^-^^^ 



:\ 



Fig. 25. — Hypoderma lineatitm.: Diagram showing position and direction of travel 

 of larvw in gullet of calf (No. 409) : A, pFeural side ; B, mucous side 



numbers in the gullet during the latter part of summer and through- 

 out the fall, however, the drawing of such a conclusion is hardly 

 justified. 



Another experimental calf (No. 409, fig. 25) which was infested 

 with about 268 eggs on the abdomen and hind legs on March 10 

 and 16 was slaughtered on July 9. A cursory examination of the 

 viscera, walls of the diaphragm, chest, and abdominal cavities failed 

 to reveal any larvae. On the gullet, however, in the submucous 

 tissue 60 larvse were found and on the muscle side of the gullet 16 

 larvse were taken in the stroma beneath the pleura. These larvse 

 ranged in length from 5 to 5.6 millimeters, but only a few were 

 carefully measured. The length of those on the pleural side of the 

 gullet was practically the same as those on the mucous side. Of those 

 m the submucous tissue 17 were pointing toward the stomach, 40 

 toward the pharynx, and 2 were not noted. On the pleural side 9 

 were pointed toward the stomach and 7 toward the pharynx. The 

 diagram (fig. 25) shows the distribution and the direction of point- 

 ing of these larvse. 



The exact course followed by the larvse in passing from the body 

 cavities to the back has not been determined with accuracy, though 

 the presence of larvse followed by greenish and gelatinous streaks 

 indicates the lines of migration and the probable routes. The find- 



