CONTENTS. 
Page. 
Summary G 
Introduction 7 
Hepatozoon perniciosum 14 
Material and technique 14 
In the blood of white rats 15 
In fresh blood 16 
In stained smears 17 
Nonsexual multiplication of H. perniciosum in the rat 18 
Clinical symptoms in rats 20 
Pathological anatomy 21 
The Arthropoda as agents in the transmission of disease 21 
Parasitic mites 23 
The Gamasidse 24 
Life history of Lelaps echidninns 25 
External anatomy oi-L. echidninns 26 
Internal anatomy of L. echidninns 27 
Sexual cycle of Hepatozoon perniciosum in the mite 30 
Experimental infection in white rats 36 
Feeding experiments 41 
Classification 43 
Conclusions 47 
( 5 ) 
