248 



THE GROUSE IN HEALTH AND IN DISEASE 



A. Sporozoite which penetrates epi- 



thelial cell of the duodenum 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 schizont. 



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. 



Q. Oocyst with contents seg- 

 mented to form four 

 rounded sporoblasts ^as 

 seen in fresh prepara- 

 tions). 



B. Oocyst with four sporo- 

 blasta which have grown 

 oval and are becoming 

 sporoeysts ; the small 

 cystal residuum seen to 

 one side. 



S. Oocyst with four spore- 

 cysts in each of which 

 two sporozoites are dif- 

 ferentiated. The oocyst 

 in this condition ulti- 

 mately opens, liberating 

 the sporocyats, the upper 

 one of which is seen 

 about to issue from the 

 oocyst. Slight cystal 

 residuum. Sporal re- 

 siduum in each sporocyst. 



T. Sporocyst which has issued 

 from oocyst. Two sporo- 

 zoites are within it and 

 have assumed the posi- 

 tion most suitable for 

 emergence. 



L. 



. Youngmacro-gameto- 

 cyte with chromatoid 

 granules. 



. Young micro-gameto- 

 cyte with fine granu- 

 lations. 



. Macro -gamete with 

 round nucleus and 

 chromatoid granules 

 distributed through 

 the cytoplasm. 



. Micro-ga metocyte 

 with nucleus divided 

 to form a large 

 number of bent rod- 

 like portions, the 

 future microgametes. 

 Remains of karyo- 

 some seen in centre. 



: . Macrogamete show- 

 ing plastinoid gran- 

 ules, the chroma - 

 toid granules being 

 largely used up in 

 forming the wall 

 with which the mac- 

 rogamete has in - 

 vested itself, the 

 remaining chroma - 

 toid granules being 

 arranged between 

 the plastinoid gran- 

 ules. 



f. Micro-gametocyte 

 with many bi-Hagel- 

 late microgametes 

 about to separate 

 from it. Karyosome 

 left at the centre. 



Fertilisation. One micro- 

 gamete is penetrating 

 the macrogamete, while 

 other male cells arc near 

 the micropyle but will be 

 excluded. 



M. Fertilisation. The male pro- 

 nucleus which entered through 

 a micropyle is lying above the 

 female chromatin. Degenerat- 

 ing microgametes are shown 

 outside the oocyst. 



N. Oocyst (encysted zygote) with 

 protoplasmic contents filling it 

 completely. Nucleus with signs 

 of fertilisation spindle. 



0. Ob'cystwith 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 cagcal droppings. 

 P. Oocyst with four nuclei. 



Diagram of Life-cycle of Eimeria (Coccidium) avium. 



D-H represent Schizogony. I-L, Gametogony. N-T, Sporogony. 



Epithelial host-cells diagrammatieally outlined. 



