OF MICRO-ORGANISMS. 15 



zoan, the flagellum of which between whiles re-entered 

 into the mass of the body, with which it mingledjit 

 was replaced by a pseudopod which soon attenuated 

 and took the form of a flagellum. 



Biitschli has recently made a very interesting ob- 

 servation on this organ of locomotion. Under certain 

 circumstances, the Peridinia (Dinoflagellates) throw off 

 their long flagellum and enter into a state of repose; 

 they generate them quite as easily. In the Glenodin- 

 iuvi cinctum, Biitschli has seen the flagellum roll itself 

 up first like a cork-screw, and then suddenly detach 

 itself from the animal; having become free, it stirs 

 about in the water for several minutes before becom- 

 ing motionless. This observation enables us to refute 

 those naturalists who believe that the vibratile cilium 

 is an appendage of the cuticle, by bringing forward 

 the fact that when the cilia with the portion of the cu- 

 ticle in which they are inserted are separated from the 

 cell, the cilia continue to move; we have just seen 

 that the flagellum moves even after it is separated 

 from the cuticle; this persistence of movement is 

 sufficiently explained by the protoplasmic nature of 

 the cilia and of the flagellum. 



From another point of view, the observation of 

 Biitschli gives us a curious example of the phe- 

 nomena of autotomy, which have recently been studied 

 by Fr6d6ricq. 



The pseudopodia, the vibratile cilia, and the flagel- 

 lum, constitute the three motor organs that are most 

 frequently found in the kingdom of the Protista. 

 Among the Infusoria, moreover, particular differentia- 

 tions of the protoplasm have been described, which 

 may be compared to the muscular fibres of the higher 

 animals. The Vorticellse are supported by contractile 



