PROTOZOA 35 
a thin cuticle; within this lies the cortical protoplasm, which, 
though full of granules, is transparent. The medullary proto- 
plasm is dark brown and opaque.  Biitschli has shown that 
some of the granules are composed of a starch-like material. 
The body exhibits movements of a euglenoid character; waves 
of contraction passing down the elongated cell. The flowing 
about of the protoplasm is rendered visible by the granules. 
The nucleus is clear and vesicular, with few granules, and it 
lies in the centre of the cell. 
At times two individuals come together and surround them- 
selves by a spherical capsule; apparently no true fusion takes 
place, but the bodies of the Gregarines commence to form spores. 
This spore formation proceeds from without imwards in each 
cell, but the whole protoplasm is not always used up for this 
purpose. The spores are shuttle-shaped, they acquire a capsule 
(chlamydospores), and are often spoken of as pseudonavicellae. 
The pseudonavicellae escape from the cyst by its bursting, or in 
Clepsidrina, a Polyeystid, by special sporoducts. Their contents 
divides into eight elongated bodies, known from their shape as 
falciform bodies ; these leave the pseudonavicella, and probably 
grow up directly into the adult form. A recent observer has, 
however, stated that the contents of the pseudonavicella does 
not break up into falciform bodies, but the protoplasm becomes 
grooved, and thus the appearance of segmentation is produced. 
According to him, the whole contents of the pseudonavicella 
escapes and grows in a new Gregarine, 
Many of the Polycystidae are more highly differentiated 
than the species described above; their cuticle may be ridged 
or tuberculated, and is frequently produced into hooks in the 
epimerite, and the cortical layer of protoplasm may show traces 
of fibrillation. When these septate forms conjugate, they 
usually lie side by side. Gregarina gigantea, which inhabits 
the alimentary canal of lobsters, attains the astonishing length 
of # of an inch, 
Coceidiidea are minute spherical cells which infest the 
epithelium of the intestine, the liver cells, etc., of Vertebrates, 
Mollusea, and Insects. Whilst still in their cell host, they 
give rise to chlamydospores and falciform young. 
