105 



(3) Four larvae were placed in the conjunctival sac. 



(4) Seven or eight larvae were placed beneath the skin of 



the animal. 



(5) Experiment (4) repeated. 



(6) Experiment (4) repeated on a, rabbit. 



Results. — No evidence was obtained suggesting that the 

 embryos or larvae were capable of penetrating the skin. There 

 was no evidence of any change in the tissues of the conjunctival 

 sac following the instillation of the larvae. A slight induration 

 was produced at the site of inoculation of the larvae. One 

 area was removed, and the microscopic examination revealed the 

 changes in the tissues mentioned above. No change was produced 

 in the tissues of the rabbit following inoculation. 



Experiments with Habronema megastoma: — 



Only one experiment was made. In this larvae were placed 

 beneath the skin, as in experiments with H. muscae. The tissue 

 reaction was the same in this case as with H. muscae. 



In the following experiments two animals were used 

 throughout. For the purpose of identification one will be 

 called pony and the other mare. 



1. Experiments with H. microstoma: — 



(a) Feeding experiments with Stomoxys calcitrant — 



Flies heavily infested with larvae were placed in a, flask, the 

 mouth of which was covered with gauze. These flies were placed 

 on a shaved area of the skin of the mare, and held in position for 

 about one hour. These experiments were made in the month of 

 June, 1918, the weather being cool. The flies did not bite very 

 readily. After the feeding operations the site was seen to be 

 somewhat swollen, which swelling had increased slightly by the 

 following morning, but rapidly disappeared during the day. 

 Another site was selected, and the experiment repeated on the 

 following day with the same results. 



The experiment was repeated on the pony with the same 

 results. 



Some months later, December, flies were placed in a cage 

 which was placed over a shaved area of the skin of the mare and 

 kept in apposition for two hours by means of bandages. This 

 experiment gave the same result as the previous experiments. 



The result of the experiments was a complete failure to pro- 

 duce a granuloma by this method. 



It was observed that the proboscides of many of the flies were 

 paralyzed, and that the flies had to a great extent lost their desire 

 and ability to bite. They fed more readily on a rabbit, but not 

 so readily as the normal flies. 



(b) Larvae placed in the skin of the horse — 



It was observed that when the proboscis was removed from a 

 fly and placed in normal saline solution kept at 37° C, the larvae 

 rapidly left the proboscis. 



It was decided to determine the ability of the larvae to 

 penetrate the subcutaneous tissues of the horse. Two small 

 incisions were made in_^the skin of the mare. The incision was 

 not so deep as to pass right through the corium. Two proboscides 

 were placed in each wound. The edges of the wound were drawn 

 together by means of adhesive plaster. The following morning, 



