ACTION OF REAGENTS OX CILIA. 65 



the movement will have become somewhat languid, 

 and then the manner in which the individual cilia 

 move can be more clearly made out. The prepara- 

 tion can be used also for the study of those agents 

 which tend to revive and stimulate ciliary motion, 

 and it will be seen that it is precisely the ones which 

 most accelerate the amoeboid movements of the white 

 blood-corpuscles that have the most marked effect 

 upon the cilia also. 



Preparation 9. Action of Warmth upon 

 Ciliary Motion. The same mode of applying heat 

 to a preparation of cilia is to be used as was employed 

 for observing the effect of warmth upon the blood 

 (p. 30). It is well, after inclosing the preparation 

 with oil (or, what is better, with melted paraffin) in 

 the manner there detailed, to put it aside for some 

 time, when it will probably he found, as just stated, 

 that the movement of the cilia is languid or alto- 

 gether arrested. On now gradually warming the 

 preparation the motion becomes revived, and as the 

 heat is raised becomes, pan passn, faster and faster, 

 until a point is reached at which the tissue is injured 

 by the high temperature, when the movement stops 

 altogether, and is not again resumed. But if the 

 experiment be stopped short of this point and the 

 source of heat removed, it will be seen that, con- 

 versely, as the temperature of the stage falls, the rate 

 of movement also diminishes, until, when again 

 quite cold, the cilia may again almost stop, although 

 they can be made to resume their active motion on 

 again applying warmth. 



"Preparation 10. Action of Weak Alkalies. 

 A very weak solution of caustic potash in salt 

 solution, like that which was used in investigating 

 the effect of weak alkalies upon the blood, is to be 

 applied to a preparation of cilia which have become 

 somewhat languid, in exactly the same manner as 

 in the case of the blood by allowing a little of the 

 fluid to pass in at the edge of the cover-glass and 

 diffuse itself with the "sea-water, so as to come 



6* 



