LIST OF ILLUSTRATIONS ix 



PAGE 



FlGS. 37 to 42. Phagocytes engulphing disease germs drawn by 



Metschnikoff 136-7 



FlG. 43. A Phagocyte containing three Spirilla, the germs of 



relapsing fever, which it has engulphed 137 



FlG. 44. The life-history of the Malaria Parasite... ... ... 142 



FlG. 45. The first blood-cell parasite described, the Lankesterella 



of Frog's blood ... ... ... ... ... ... 144 



FIG. 46. Various kinds of Trypanosomes 145 



FlG. 47. The Laboratory of the Marine Biological Association 



on the Citadel Hill, Plymouth 155 



FlG. 48. The Tsetze fly, Glossina morsitans ... ... ... 172 



FIG. 49. The Trypanosome of Frog's blood ... ... ... 173 



FIG. 50 The Trypanosome which causes the Sleeping Sickness 176 

 FIG. 51. The Trypanosome of the disease called " Dourine" ... 177 

 FlGS. 52 to 56. Stages in the growth and multiplication of a 

 Trypanosome which lives for part of its life in the 

 blood of the little owl, Athene noctua, and for the 

 other part in the gut of the common Gnat (Culex} 180-3 



