34 



ZOOLOGY 



emerging and living parasitically in the various cavities of 

 their host. The Coccidiidea pass their whole life as, cell 

 parasites. The true Gregarines are divided into the Mono- 

 cystidae, whose body is not divided into two chambers, and 

 which inhabit Annelids, Gephyrea, Platyhelminthes, and Tuni- 

 cata; and the Polycystidae, in which a transverse partition 

 divides the cell into an anterior and posterior chamber, the 

 latter invariably containing the nucleus. An anterior outgrowth, 

 the epimerite, which serves to attach the Gregarine to the tissues 

 of its host, is often present, but this is shed sooner or later. 

 The Polycystidae have hitherto only been found in the 

 alimentary canal of Arthropods. 



Monocystis magna (Pig. 27) is frequently to be found with its 

 anterior end embedded in one of the epithelial cells of the en- 



¥m. 27. — Five individuals of Monocystis irmgna (Schmidt), with their anterior 

 ends embedded in the cells of the rosette-shaped inner end of the vas deferens of 

 Lu/mJbricus Urrestris. 



1. Part of the vas deferens of L. 3. The nucleus. 



terrestris. i. The ectoplasm. 



2. The endoplasm of the Gregarine. 5. The cuticle. 



larged inner rosette-shaped openings of the vas deferens of the 

 common earthworm. It is visible to the , naked eye, and 

 sometimes attains a length of 5 mm. The body is limited by 



