CIRCULATION OF THE BLOOD. 367 



standing perfectly flat. The bandage should be from eight 

 inches to a foot in length, and half-an-inch or more in width ; 

 a small piece of it should be laid in the bottom of the 

 trough, and upon this the fish is to be placed horizontally, 

 the bandage may then be wound round the cell and the 

 body of the fish, to secure it from kicking very much, 

 but not so tight as to stop the circulation, taking care 

 that all the turns are within the recess left between the 

 strips of glass, as shown by d in fig. 239. Some water is 

 now to be added, so as nearly to fill the cell, and the tail of 

 the fish is to be spread out as shown at yin fig. 238. In 

 order to prevent the tail from being flapped up against the 

 object-glass, a thin piece of brass or other metal of either 

 of the shapes represented by a or i in fig. 240, is to be 

 placed over the body of the fish, the 

 large end being turned towards the 

 head, and the small so arranged as to 

 cover the commencement of the tail, 

 as shown in fig. 238 at ff, and in fig. 

 239 at e. The metal may be secured 

 Fig. 240. by the bandage, but it should not be 



so long as to cover the entire length 

 of the fish, but only about half-an-inch of the caudal 

 extremity, otherwise the movements of the body cannot 

 be entirely controlled. In order to prevent any of the 

 water from being splashed out of the cell, and also to secure 

 the object-glass from having any moisture condensed upon 

 it, that part of the cell immediately over the tail may be 

 covered with a piece of thin glass, which wiU answer both 

 purposes ; the cell must be nearly fuU when the glass is laid 

 on, otherwise if a stratum of air intervene between the water 

 and the thin glass, correct definition cannot be obtained. 



Circulation of Blood in the Frog. — The part most commonly 

 employed for this purpose is the transpairent web of the hind 

 foot; and in order to secure the animal, and keep its web 

 open, various contrivances have been had recourse to. The 

 older microscopists, as seen in the works of Baker and Adams, 

 were in the habit of tying the frog to a frame of brass with 



