STRUCTUEE AND LIFE-HISTORY OF CRITHIDIA MELOPHAGIA. 189 



The Structure and Life-History of Crithidia 

 melophagia (Flu), an Endo-parasite of the 

 Sheep-Ked, Melophagus ovinus. 



By 



Annie Porter, B.Sc.Loncl., 



Zoological Research Laboratory, University College, London. 



With Plates 12 and 13 and 15 Text-figures. 



Consents. 



Introduction 

 Material and Methods 

 Distribution of Parasites in the Host 

 Movements 



Morphology : Pre-flagellate Stage . 

 Flagellate Stage 



Post-flagellate Stage in the Rectum of 

 the Host 

 Longitudinal Division 

 Hereditary Infection of Melophagus ovinus by C 



melophagia 

 Casual Infection . 

 Environmental Effects 

 General Remarks 

 Summary 

 Appendix I. — On the Occurrence of a Spii'ochsete (S. 



melophagi, n. sp.) in Melophagus ovinus 

 Appendix II. — Note on a Fungus found in the Mal- 



jjighian Tubules and Intestine of Melophagus 



ovinus 

 Appendix III.— On the Occurrence of an Anti-coagulin 



in the Alimentary Canal of Melophagus ovinus, 



and its Significance in Relation to Crithidia 



melophagia .... 



References to Literature .... 

 Explanation of Plates .... 

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