80 PHYSIOLOGY OP THE DOMESTIC ANIMALS. 



ciliated surfaces is evidently dependent upon the fact that the intensity 

 of motion is greater in one direction than in the other ; otherwise, of 

 course, the effect would be negative. 



Since ciliated epithelium, as has been already shown, lines most of 

 the tubular structures of the animal body, the effect of the vibratory 

 motion of the cilia will be to propel onward fluids and light particles in 

 contact with the surfaces of the membrane. Thus, the cilia of the 

 Fallopian tube, by their vibrations, serve greatly to assist the onward 

 passage of the ovum through the oviduct. 



Ciliary motion persists only as long as the cilia are in contact with 

 the protoplasmic contents of cells, although Briicke has found that it is 

 not necessary that the entire cell be in contact with the cilia ; for if the 

 free surface of a ciliated membrane is carefully shaved with a sharp 

 knife and the portions cut off examined under a microscope, it will be 

 found that many of the ciliated cells have been divided, and yet, provided 

 a certain portion of the cell-contents is still in contact with the cilia, the 

 latter will still manifest their normal movements. Ciliary movement 

 may persist after the death of the individual where that ciliary motion 

 is not concerned in producing movement of the entire organism ; thus, 

 in the ciliated infusoria anything which destroys the life of the animal- 

 cules will arrest ciliary movement; but, in the higher animals, in the 

 cold-blooded groups, motion of ciliated epithelium may persist for days 

 after the death of the animal; while, even in the warm-blooded animals, 

 a number of hours after the death of the organism, the cilia will still be 

 in vibration. This indicates that, in the first place, ciliary movement is 

 not under the control of the nervous system; and, secondly, that it is 

 independent of the state of the entire organism, — at any rate, in the 

 higher forms of life, — since it may persist long after the irritability of 

 nerves and muscles has disappeared. Temperature produces the same 

 effects, nearly, on ciliary movement as it exerts on other protoplasmic 

 movements ; thus above 45° C: ciliated motion ceases, while at 0° C. it 

 also is arrested, to, however, return again when the temperature is raised. 



Increase of temperature between these two limits produces increase 

 in the rapidity of oscillation of cilia, while decrease of the temperature 

 produces retardation. 



Every alteration in degree of watery imbibition of epithelial cells 

 exerts an influence on the ciliary movement ; especially on the degree of 

 frequency and amplitude of vibration. Increasing the amount of water 

 in the epithelial cells above the normal amount may, at first, increase the 

 vigor of oscillation, but when a certain maximum is passed motion is 

 gradually arrested, as in heat-tetanus ; the cilia coming to rest while bent 

 forward, both cells and cilia being swollen and more transparent, and the 

 nucleus appearing as a distended, watery vesicle. When such a con- 



