"GROUSE DISEASE " COCCIDIOSIS 251 



EXPLANATION OF ^TEXT-FIG. 36. 



A. Sporozoite or primary infecting germ, which penetrates an epithelial cell of the 



duodenum of the host. 



B. Sporozoite curving on itself before becoming rounded within the host-cell. 



C. Young, growing and feeding form, the trophozoite. 



D. Fully grown trophozoite or uninucleate schizont, which is about to begin to divide. 



E. Schizont or dividing form with numerous daughter nuclei arranged at the edge, 



beginning to form merozoites or daughter forms. 



P. Schizont showing further differentiation of merozoites. 



G. Merozoites arranged like the segments of an orange ("en barillet"), about to issue 

 from host-cell. At one end of the cluster, residual protoplasm is seen. 



H. Free merozoites, each of which can attack a fresh epithelial cell. 

 I. 9 Young female mother cell or macro-gametocyte. 

 c . Young male-parent cell or micro-gametocyte. 



J. ? . Macrogamete or female form with round nucleus and colourable granules dis- 

 tributed through its body substance. 



c. Micro-gametocyte (male-parent cell) with nucleus divided to form a large number 

 of bent rod-like portions, the future microgametes or males. 



K. 9 Macrogamete or female, showing food granules, the colourable granules being 

 largely used up in forming the wall with which the female has invested itself. 



c. Micro-gametocyte (male-parent cell) with many microgametes (males) about to 

 separate from it. 



L. Fertilisation. One microgamete (male) is penetrating the macrogamete (female), 

 while other male cells are near the micropyle or pore but will be excluded. 



M. Fertilisation. The male pronucleus which entered through a micropyle is lying above 

 the female pronucleus. Degenerating microgametea (males) are shown outside the 

 oocyst. 



N. Oocyst (or cyst) with contents filling it completely. Nucleus in centre composed 

 of fused male and female reproductive substance. 



0. 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 csecal 

 droppings. 



P. Oocyst with four nuclei beginning of division to form. four spores. 



Q. Oocyst with contents segmented to form four rounded sporoblasts or young spores 

 (as seen in fresh preparations). 



R. Oocyst with four sporoblasts (young spores) which have grown oval and are becoming 

 sporocysts or mature spores ; the small cystal residuum seen to one side. 



S. Oocyst with four sporocysts (spores) in each of which two sporozoites are differentiated. 



The oocyst in this condition ultimately opens, liberating the sporocysts, the upper 



one of which is seen about to issue from the oocyst. Slight cystal residuum. 



Sporal residuum in each sporocyst. 

 T. Sporocyst or spore which has issued from oocyst. Two sporozoites or infecting germs 



are within it, and have assumed the position most suitable for emergence. 



