62 



PROTOZOOLOGY 



ranged skeletal fibrils (Fig. 15). The contraction of the stalk is 

 brought about by the action of kinoplasm and walls, while elastic 

 rods will lead to extension of the stalk. Myonemes present in the 

 ciliates aid in the contraction of body, but those which occur in 

 many Gregarinida aid apparently in locomotion, being arranged 

 longitudinally, transversely and probably spirally (Roskin and 

 Levinsohn, 1929) (Fig. 15, c). In certain Radiolaria, such as Acantho- 



Fig. 15. a, b, fibrillar structures of the stalk of Zoothamnium (Kolt- 

 zoff); c, myonemes in Gregarina (Schneider), ef, elastic fiber; ie, inner 

 envelope; k, kinoplasm; oe, outer envelope; t, thecoplasm. 



metron elasticum (Fig. 219, c), etc., each axial spine is connected with 

 10-30 myonemes (myophrisks) originating in the body surface. 

 When these myonemes contract, the body volume is increased, thus 

 in this case functioning as a hydrostatic organella. 



In Isotricha prostoma and /. intestinalis, Schuberg (1888) observed 

 that the nucleus is suspended by ectoplasmic fibrils and called the 

 apparatus karyophore. In some forms these fibrils are replaced by 

 ectoplasmic membranes as in Nyctotherus ovalis (Zulueta; Kudo), 

 ten Kate (1927, 1928) studied fibrillar systems in Opalina, Nycto- 



