NEUEOID TRANSMISSION 



69 



20 



0-2 



20' 



a sheet of ciliated epithelium could cover all three areas, 

 and the epithelium was always so placed that the axis cor- 

 responding to the direction of its ciliary waves passed 

 over all three chambers. When the two 

 end chambers contained water at 20 C. 

 and the intermediate chamber water at 

 to 2 C., the cilia beat continuously 

 from one end of the membrane to the 

 other. When, however, the temperature 

 of the two end chambers was reduced to 

 from 10 to 12 C., the cilia over these 

 chambers beat at a very slow rate, one 

 to two strokes per second, and those over 

 the middle chamber were entirely qui- 

 escent. If now the cilia over the first end 

 chamber were stimulated to greater ac- 

 tivity by stroking them gently with a fine 

 brush, increased activity soon appeared 

 in those over the other end chamber, 

 though the cilia over the intermediate region remained 

 entirely motionless. Thus a form of transmission other 

 than that carried out by the mechanical activity of the 

 cilia must be admitted to have taken place over the area 

 between the two extremes. 



A second experimental test was carried out by Kraft 

 with the apparatus just described, but with the use of a 

 temperature not a mechanical stimulus. In this test the 

 two end chambers were set at 10 C. and the intermedi- 

 ate chamber was kept so cold that the cilia over it did not 

 beat. Those over the end chambers beat only slightly. 

 The temperature in the first chamber was then raised 

 from its original point of 10 C. to 15 C. and the cilia 

 over this chamber now began to beat more rapidly than 



Fio. 16. Plan of a 

 temperature box divid- 

 ed into three chambers, 

 each of which can be 

 kept constant by a flow 

 of water. The box is of 

 such a size as to allow a 

 piece of ciliated epithe- 

 lium to be spread over 

 the three temperature 

 areas as in the experi- 

 ment by Kraft. 



