412 



THE MICROSCOPE. 



The Gillet's condenser, or parabolic reflector, will do equally well with 

 a l-8th objective. In diagram A, fig. 195, is given a sketch of a speci- 

 men of the C. Lunula ; with the above arrangement of microscopic 



fig. 195. 



power, and a deep eye-piece, the cilia will be seen in full action 

 along the edge of the membrane which encloses the endochrome ; and 

 also, but not so distinctly, along the inside of the edges of the frond 

 itself. Their action is precisely the same as that in the branchiae of 

 the mussel : there is the same wavy motion ; and as the water dries 

 up between the glasses in which the specimen is enclosed, the cir- 

 culation becomes fainter, and the cilia are seen with more distinct- 

 ness. 



In diagram A, a line is drawn at & to a small oval mark ; these 

 exist at intervals, and more or less in number over the surface of the 

 endochrome itself, beneath the membrane which invests it. These 

 seem to be attached by small pedicles, and are usually seen in motion 

 on the spot to which they are thus fastened ; from time to time they 

 break away, and are carried by the circulation of the fluid, which works 

 all over the endochrome, to the chambers at the extremities ; there they 

 join a crowd of similar bodies, each in action within those chambers 

 when the specimen is a healthy one. 



The circulation, when made out over the centre of the frond, for 

 instance at a, is in appearance of a wholly different nature from that 



