1 62 HOW TO WORK 



single cilium may be watched, in which case the observer may 

 demonstrate the interesting fact that movement occurs not only at 

 the base of the cilium, but in every part of the vibratile filament. 



Of all the ciliated structures, the newt's kidney is perhaps the 

 most beautiful and the most remarkable. The tortuous uriniferous 

 tubes in the upper thin portion of the kidney are lined in their whole 

 length with ciliated epithelium, which continues in active motion for 

 some time after the removal of the organ from the body of the 

 animal. In order to display this wonderful object, we must proceed 

 as follows : After destroying the newt by decapitation, the abdominal 

 cavity is laid open, and by turning the viscera to one or other side, 

 the kidneys may be exposed. Towards the pelvis, the kidney pre- 

 sents much the same appearance as in the frog : but, upon tracing it 

 upwards, it will be found to become gradually thinner, and to extend 

 quite into the thoracic portion of the animal. It is this upper thin 

 part of the kidney which shows the ciliary motion to the greatest 

 advantage. Sec pi. XXXIII, fig. 218. A probe, a, is represented 

 in the drawing underneath that portion of the kidney which should 

 be examined in the microscope. The secreting tubes lie upon one 

 plane, so that a tube, throughout the entire length of which active 

 ciliary motion is constantly taking place, may often be seen in the 

 field of the microscope at one time. A more beautiful object under 

 a half-inch object-glass, can scarcely be conceived. The thin 

 portion of the kidney, above referred to, is to be very carefully 

 removed from the body by delicate manipulation with fine forceps 

 and a pair of scissars, moistened with a little water, or, what is still 

 better, with some of the serum of the animal, placed in a large 

 thin glass cell, and carefully covered with thin glass. The cell should 

 be sufficiently thick to prevent any pressure upon the preparation. 

 After ciliary motion has stopped, the cilia are with great difficulty 

 distinguished. Many of the tubes in the lower thick part of the 

 kidney do not exhibit ciliary action perhaps because the cells are 

 undergoing degeneration. I have been able to find tubes in every 

 stage of wasting in newts which have been kept in confinement. 



Ciliated epithelium may be obtained from the larynx and trachaea 

 of man by coughing violently. The vibration occasionally continues 

 for some time after the specimen has been transferred to the glass 

 slide. The observer will be surprised at the enormous number of 

 cilia projecting from a single cell ; indeed it often happens that a 

 mass is expelled which seems to consist of hundreds of long 

 filaments, all in active vibration, radiating from a common point. 



Ciliary action is, I think, due to changes going on within the 

 cell, but probably very intimately connected with the currents which 



