210 ANNIE POKTEU. 



(7) Dilute glycerine killed C. melophagia almost at 

 once. Vaseline had the same effect after a very short time. 



(4) Effect of a parasitic fungus of Melophagus 

 ovinus on C. melophngia. — The presence of a fungus in 

 Melophagus ovinus has already been mentioned. As I 

 very rarely found the fungus and Crithidia co-existing in a 

 ked, it was deemed advisable to find out any possible inter- 

 relation of the two parasites. The Malpighian tubules of the 

 ked — often blocked with fungus — were the most heavily 

 infected organs. Fungus taken from the ^lalpighian tubes 

 was crushed with a little water. The emulsion, which 

 probably contained an enzyme, was added to a preparation of 

 actively moving C. melophagia. The movements of the 

 flagellates slowed at once, their protoplasm became much 

 more vacuolated, and the parasites appeared to burst. After 

 seven to nine minutes no living Crithidia were to be seen. 



The fungus-infected Melophagus ovinus seems widely 

 distributed. Specimens from Scotland were practically 

 always heavily infected with it, and some keds from each 

 locality tried in England also were infected. These keds 

 very rarely contained Crithidia. The fungus seems to 

 have a pathogenic action npon the flagellate, and I believe 

 that the co-existence of the fungus and Crithidia for long 

 together is almost impossible. 



General Remarks. 



Regarding the previous work done on the genus Crithidia, 

 I have already noted most of the memoirs dealing with the 

 subject in my paper on Crithidia gerridis (1909). Conse- 

 quently the remarks now appended relate especially to the 

 flagellate of Melophagus ovinus. 



E. Pfeiffer (1905) first briefly described a flagellate as 

 occurring in the gut of Melophagus ovinus. He mentions 

 that L. Pfeiffer had seen and recorded the parasite in 1895. 

 The flagellate stage only was described, and no definite name 

 was given to the organism, which was stated to be "like a 

 trypanosome." 



