CILIARY ACTIVITY 



29 



activity of the cell. But the same is true of a rhythmically 

 contractile muscle such as that of the heart. 



Engelmann maintained many years ago that the ciliated 

 epithelium of the frog's oesophagus remains active for as long 

 as two hours in an atmosphere of hydrogen, but regarded this 



TEMPERATURE 



Fig. 10. — The relation of oxygen consumption and mechanical activity of 

 cilia to temperature (after Gray). 



as evidence that the cell stored oxygen in some intramolecular 

 form. By spectroscopic examination of water in which 

 haemoglobin was dissolved, Gray has proved conclusively that 

 in the gills of Mytilus ciliary movement continues long after 

 all oxygen has been removed from the medium. When 

 ultimately brought to rest by this means recovery is very slow, 



