274 BRANSON, ON CILIARY ACTION. 



On, Ciliary Action as the cause of the Circulation in the 

 Cells of Plants. By Ferguson Branson, M,D,, Sheffield. 



The cause of the circulation of the granules of chlorophyll 

 in the cells of certain plants has hitherto been involved in 

 mystery. I have spent many hours in examining the circula- 

 tion in the cells of the Anacharis alsinastrurn, the new water- 

 weed ; and in October, 1854, I first observed a distinct ciliary 

 wave at the edge of the outermost cells. Repeated examina- 

 tions have satisfied me that the rotatory movements depend 

 upon cilia attached to the inner surface of the cell-wall. The 

 cilia are extremely minute, and require the highest powers of 

 the microscope, combined with very " happy " illumination, 

 to display their waving motion. The ciliary wave can only 

 be seen under very good daylight, or by means of the best 

 artificial illumination. In the Anacharis the cells best cal- 

 culated to display the ciliary wave are those at the edge of 

 the leaflet ; for here a single layer of cells exists, and no 

 deception can occur from the movements in the cells beneath. 

 A leaflet should be selected in which the granules are just 

 beginning to move, or rather have not got into rapid motion ; 

 the ciliary movement is then less active, and, consequently, 

 can be more readily seen. The microscope must be very 

 accurately adjusted in order to define the wave, and even 

 then the observer's patience may be severely tried before he 

 is rewarded with a sight so interesting and remarkable. A 

 cell in which a large number of granules are circulating 

 should not be selected for observation; the greater the number 

 of granules the moi'e will the view be obstructed and confused. 

 I have used an eighth of an inch object-glass, by Powell and 

 Lealand, aided by their improved achromatic condenser, and 

 a No. 2 eye-piece. A power less than this will not define 

 the ciliary wave. The diaphragms used are numbered 4 and 

 5 on the condenser. A diaphragm with a central stop — ab- 

 solutely necessary for resolving the more difficult Navicular — 

 will not display the cilia. I am the more minute on this 

 point, for without great attention to the manipulation the 

 wave will not be seen. The cilia are extremely minute, pro- 

 bably not much larger than the dots on some of the Naviculae, 

 and much more difficult to illuminate satisfactorily. It may 

 be said that cilia so minute could not draw to the side of the 

 cell, and then impel around it the large granules of chloro- 

 phyll which float within it. Let any one place a small 

 portion of cork or paper in the centre of a large basin of 

 water, and when the water is perfectly at rest gently agitate 

 it in one direction at the side of the basin, and the cork 



