PARASITIC PROTOZOA IN RELATION TO THE WAR. 3II 



tial. European houses should be situated well away from native 

 quarters, as native children can act as reservoirs of malarial 

 parasites, they themselves being relatively immune from their 

 effects. Former sufferers from malaria, who are still subject to 

 relapses, may be responsible for new malarial outbreaks, if they 

 live in districts where transmitting ;\nophelines occur. 



In this paper, the importance of parasite carriers and reser- 

 voir hosts as potential dangers has been frequently mentioned. 

 But the very existence of such parasite carriers has also a re- 

 assuring side, in that il indicates that pathogenic properties among 

 parasitic Protozoa may work themselves out — in other words, 

 that non-pathogenic strains may be produced in time. This is 

 due to the gradual establishment of a mutual tolerance between 

 the host and the parasite, whereby they live in harmony with one 

 another. It is obviously to the disadvantage of the parasite to 

 bring about the premature death of its host, and therebv shorten 

 its own existence. Mutual tolerance, relative immunity and the 

 gradual production of non-])athogenic strains all afford illus- 

 trations of the Balance of Nature. 



Figs. T, 2. — Uniamaha histolytica. Fig. i. Trophozoite showing nucleus 



with karyosome and centriole. and two ingested red blood-corpuscles. 



X 1..SOO. Fig 2, Typical cyst with four nuclei and chrnmatoid body. 



X 2,000. 

 Fig- 3- — Entamoeba coli. Typical cyst with eight nuclei. X 2,000. » 



Fig. 4. — Trichomonas hominis. Flagellate form. X 2,000. 

 Figs. 5 to 7. — Chilomastix mesnili. Fig. 5, Flagellate form. Fig. 6, Oval 



cyst. Fig. 7. Lemon-shaped cyst. X 2,500. 

 Figs. 8, 9. — Giardia intesti)ialis. Fig. 8. Flagellate form. Fig. 9. Cyst. 



X 2,500. 

 Fig. ID. — Spirochceta curygyrata. Motile form with diffuse nucleus. 



X 3,000. 

 Fig. II. — Isospora hominis. Oocyst containing two sporocysts, each 



containing four sporo^oitc.s. X t,ooo. 

 Fig. 12. — Eimeria sticdcr. Oocyst containing four sporocysts, each with 



two sporozoites. X t.ooo. 

 Fig. 13. — BalantidiuDi coli. — Ciliate form. X 1,000. 

 Fig. 14. — Trypanosoma gainbicnse. Flagellate form. X 2.000. 

 Fig. 15. — Trypanosoma rhodesiense. Flagellate form with posterior 



nucleus. X 2,000. 

 Figs. 16, 17. — Leishmania donovani. Fig. 16, Herpetomonad stage. Fig. 



17, Non-tiagellate stage or Leishman-Donovan body. X 1,500. 

 Figs. 18 to 21. — Plasmodium vivax. — Fig. r8. Young ring form within red 



blood-corpuscle. F'ig. 19. Amoeboid parasite showing pigment 



Fig. 20, Multiplying form or schizont. Fig. 21, Cluster or rosette of 



merozoites within the red blood-corpuscle X 3,ooo. 

 Figs. 22. 23. — Laverania malarice. Cre.scent-shaped gametocytes. Fig. 22, 

 Male gametocyte. Fig. 22,, Female gametocyte. X 3.000. 



{Read July 3, 1917.) 



