THE INFECTIVE SPORES 



129 



secrete a coat for themselves, when they are known 

 as the sporocysts or spores. Each oocyst, then, 

 contains four sporocysts (Figs. 28, S ; 29, F). 



The spores do not remain undifferentiated for 

 long. A rounded or oval shining area makes its 



E. 



F. 



OF 



FIG. 29 STAGES IN THE DEVELOPMENT OF THE OOCYSTS 

 ElMERIA AVIUM, AS SEEN IN FRESH PREPARATIONS 



A , Oocyst, with protoplasm completely filling it ; J5, older oocyst 

 with contents forming a central sphere; C, oocyst with four 

 nuclei about to form sporoblasts ; D, oocyst with four round 

 sporoblasts ; E, four ovoid sporocysts within oocyst ; F, fully 

 mature oocyst with four sporocysts or spores, each containing 

 two sporozoites 



appearance in them, and at the same time the 

 nucleus becomes bowed and dumb-bell-like. The 

 shining area becomes filled with liquid, and the 

 vacuole so produced gradually extends obliquely 

 until it has cleft the protoplasm and nucleus into 

 9 



