MONOCYSTIS 



157 



as the divisions of an orange are arranged round the central 

 fibrous axis. These minute bodies, called the sporozoites, 

 or sometimes the falciform (i.e. sickle-shaped) young, are 



Fig. 33- 



A , Conjugation of two zygotes of Monocystis agilis showing, the 

 nuclei and the partition wall between the zygotes. B, 

 formation of the polar body, visible in one of the zygotes 

 only. C, approximation of the nuclei of the two zygotes 

 after formation of the polar bodies. D, two zygotes 

 showing division of the nuclei derived from the combination 

 nucleus. , Two zygotes surrounded by a capsule, f, a 

 pseudonavicella containing eight sporozoites. (After 

 Wolters.) 



liberated, and enter the sperm-mother cells of the same, or 

 another, earthworm ; but their actual history at this stage 

 has not been traced. It is probable that, after rupture of the 

 cyst-wall, the sporozoites escape by bursting out of the 



