248 



THE GROUSE IN HEALTH AND IN DISEASE 



A. Sporozoite which penetrates epi- 



thelial cell of the duodeDum of 

 the host. 



B. Sporozoite curving on itself before 



becoming rounded within the 

 host-cell. 



C. Young, uni-nucleate trophozoite. 



D. Fully grown trophozoite or uni- 



nucleate Echizont. 



Text-Fig. 1. 



E. Schizont with numerous daughter 



nuclei peripherally arranged, 

 differentiating to form mero- 

 zoites (seen in transverse sec- 

 tion). 



F. Schizont showing further differ- 



entiation of merozoites (seen in 

 oblique section). 



G. Merozoites arranged "enbarillet," 



about to issue from host-cell. 

 At one end of the cluster 

 residual protoplasm is seen. 

 H. Free merozoites, each with a 

 small karyosome. 



Oocyst with contents seg- 

 mented to form four 

 rounded sporoblasts (as 

 seen in fresh prepara- 

 tions). 



, Oocyst with four sporo- 

 blasts wliich have grown 

 oval and are becoming 

 sporocysta ; the small 

 cystal residuum seen to 

 one side, 

 Obcj'st with four sporo- 

 cysts in each of which 

 two sporozoites are dif- 

 ferentiated. The uiicyst 

 in this condition ulti- 

 mately opens, liberating 

 the sporocysts, the upper 

 one of which is seen 

 about to issue from the 

 oocyst. Slight cystal 

 residuum. Wporal re- 

 siduumineachsporocyst. 



, Sporocyst which has issued 

 from oocyst. Twosporo- 

 zoites are within it and 

 have assumed the posi- 

 tion most suitable for 

 emergence. 



5. Youngmacro-gameto- 

 cyte with chromatoid 

 granules. 



(J . Young micro-gameto- 

 cyte with tine granu- 

 lations. 



X- Macro -gamete with 

 round nucleus and 

 chromatoid granules 

 distributed through 

 the cytoplasm. 



cJ. Micro-ga nietocyte 

 with nucleus divided 

 to form a large 

 number of bent rod- 

 like portions, the 

 future microgametes. 

 Remains of karyo- 

 some seen in centre. 



V • Macrogamete show- 

 ing plastinoid gran- 

 ules, the chroma - 

 toid granules being 

 largely Ubed up in 

 forming the wall 

 with which the mac- 

 rogamete ha.-^ in - 

 vested itself, the 

 remaining chroma - 

 toid granules being 

 arranged l>etw^een 

 the pla.<:tinoid gmn- 

 ules. 

 J. Micro-gametocyte 

 with many bi-flagel- 

 late microgametes 

 about to separate 

 from it. Karyosome 

 left at the centre. 



Fertilisiition. One micro- 

 gamete is penetrating 

 the macrogamete, while 

 other male cells arc near 

 the micropylc but will be 

 excluded. 



Fertilisation. The male pro- 

 nucleus which entered through 

 a micropylc is lying above the 

 female chromatin. Degenerat- 

 ing microgametes are shown 

 outside the oocyst. 



. Oiicyst (encysted zygote) with 

 protoplasmic contents tilling it 

 completely. Nucleus with signs 

 of fertilisation sjundle, 



, Oocyst with contents concentrated, 

 forming a central spherical mass 



which has a vacuole in the 

 middle and the nucleus to one 

 side. Many such cysts seen in 

 infected ca-cal droi»pings, 

 P. Oticyst with four nuclei. 



Diagram of Life-cycle of Eiineria {Coccidium) avium. 



D-11 reprcvsent Scliizogony. 1-L, Gainetogoiiy. N-T, Sporogoiiy. 



Epithelial host-cells diagrammatical ly outlined. 



