98 



from, about the posterior part of the oesophagus. The tail was 

 pointed and possessed a small rounded tip furnished with 

 minute spines. The anus was open and situated 83'3 jut, from 

 the point of the tail. The pharynx was 43 '3 jul long; the nerve 

 ring 130 /x from the anterior end of the body, and the 

 anterior portion of the oesophagus 133 /x to 140 ju, long. 



The larvae were embedded in paraffin and sectioned. On 

 transverse section the cuticle was found to be traversed by fine 

 longitudinal ridges. These numbered from forty to forty- 

 two, as near as could be determined ; started immediately 

 behind the head and ended near the tail. 



Experiments were undertaken to determine the power of 

 the larvae to leave the proboscis of the fly. Flies were placed 

 in an inverted wide-mouthed Florence flask. The mouth of the 

 flask was surrounded by gauze, which also surrounded the 

 mouth of a test tube situated several inches below and con- 

 taining sugar dissolved in water. This test tube was kept filled 

 with the solution, which was examined from time to time for 

 the presence of larvae. The flies drank freely of the solution, 

 but at no time were any larvae found to have escaped into the 

 solution . 



In one case two flies kept overnight in a test tube contain- 

 ing a small amount of sugar solution were found to be dead 

 the following morning. Two active larvae were found in the 

 solution. It is not possible to say whether the larvae left the 

 proboscis during the life of the fly or after its death. Dead 

 flies have been placed in saline solution, and later larvae have 

 been found in the solution. 



In making a careful removal of the proboscis from the 

 head it has sometimes been observed that the larvae will escape 

 through the lips of the proboscis. This is probably due to 

 rupture of the proboscis during handling rendering it possible 

 for the larvae to escape from their situation in the muscular 

 portion into the food canal. 



Experiments were made to determine whether larvae are 

 capable of penetrating filter paper. A short test tube was 

 filled with saline solution, or a mixture of saline and horse 

 serum, and a folded filter paper (very small size) was fitted 

 into the mouth of the tube. Larvae were placed in the fluid 

 contained in the cup formed by the folded paper. This 

 preparation was kept at room temperature or 37° C. for 

 twenty-four hours in a moist chamber, and the fluid in the test 

 tube examined for the presence of larvae. On one occasion 

 two larvae were found in the fluid. This finding could not be 

 confirmed after repeated experiments. 



The larvae were found to remain alive in saline solution 

 or horse serum for forty-eight hours, and sometimes up to 

 seventy-two hours. 



