CIRCULATION IN TAIL OP NEWT. 593 



mouth and the bottom ; and the mouth itself capable of 

 being closed by a drawing-in string, d d. Into this bag 

 the frog is placed, and only the leg which is about to 

 be examined kept out of the mouth; the string dd is 

 then to be drawn so tight around the small part of 

 the leg, as to prevent the foot from being pulled into 

 the bag, but not to stop the circulation; three short 

 pieces of thread, ///, are now to be passed around the 

 three principal toes; and the bag with the frog is to 

 be fastened to the plate a a by means of the tapes c c. 

 When this is accomplished, the threads /// are to be 

 passed either through some of the holes in the edge of the 

 plate, three of which are shown at g g g, in order to keep 

 the web open ; or, what answers better, in a series of pegs 

 of the shape represented by h, each having a slit i extend- 

 ing more than half-way down it; the threads are wound 

 round these two or three times, and then the end is 

 secured by putting it into the slit i. The plate is now 

 ready to be adapted to the stage of the microscope : the 

 square hole upon which the foot must be placed is brought 

 over the aperture in the stage through which the light 

 passes to the object-glass, so that the web may be strongly 

 illuminated by the mirror. The power required to view 

 the circulation will be a one-inch or half-inch object-glass; 

 a higher power will be needed to show the rhythm in the 

 veins. 



In the common Newt, as well as the Frog, the circulation 

 may be viewed : the tail of the young animal being much 



Fig. 329. -The Triton, or Lissotriton ; Newt, or Eft: male. 



Q Q 



