NOTES ON SOME OF THE APPARATUS 469 



them. Subtract algebraically this average from each measurement. 

 (Place all the arithmetical work in the note-books.) Use the same method 

 in comparing the speed on the warmed mucosa, and state the acceleration 

 in percentage of the cold rate. 



Note (1) the direction, (2) the speed, and (3) the great power of the 

 ciliary motion (Bowditch). 



Expt. 21. Coordination of Cellular Movement. (Apparatus: Frog- 

 board, powdered charcoal, hot wire.) With the heated wire superficially 

 cauterize a spot of the ciliated mucous membrane which has been lightly 

 powdered with charcoal. Observe carefully where there is movement 

 still and where it is not. It will be found that the motion is stopped not 

 only on the burned spot, but throughout a small isosceles triangle whose 

 apex is at the spot and whose base is toward the esophagus. 



Most of the infusoria we have been studying move by means of cilia; 

 so do spermatozoa. Ciliated epithelium lines the human air-passages, 

 the Fallopian tubes, the cerebral ventricles, the ventricle of the cord, 

 the Eustachian tube, the vasa efferentia, etc. Its general function is to 

 move a liquid or small particles over a surface or through a tube. Nerves 

 are probably nowise concerned. 



The cause of the movement of cilia lies in the body of the cell from 

 which they extend, for they have no power of movement when separated 

 from their cells; probably the nucleus exerts the control in some way. 

 Cilia have a rhythm which is broken only by external influences or when 

 the cell is about to rest. Another conspicuous quality of the movement 

 of cilia is the progression of the bending movement from one cilium to 

 the next, each phase being represented by many different cilia at the same 

 time; different rows of cells are coordinated in this rhythm. 



The active or contractile movement of the cilia is probably the erecting 

 phase and not the phase in which it bends downward, for this latter corre- 

 sponds to relaxation. The contractile phase is quicker than the other; 

 contraction of the side of the cilium convex in its resting position pulls 

 the cilium to a vertical position. Reversal of the movement is sometimes 

 observed, but never, so far, in vertebrates. (Consult the literature in 

 the libraries, especially Verworn). 



III. NOTES ON SOME OF THE APPARATUS. 



Review discussion of electrical physics and demonstration of the galvanic 

 cell, the inductorium, the rheocord, the chronograph, PohPs commutator, 

 the muscle-lever, the electro-magnetic signal, the non-polarizable 

 electrode, the capillary electrometer, the tuning-fork, etc. 



However much a student may know about physics (and it is 

 almost always far too little), it is necessary to learn the theory and 

 practice of the simple apparatus used in experimental physiology, else 

 much time and material will be wasted. In this work several matters 

 respecting electrical apparatus are essential which elsewhere often are 



