THE ADDEK. 149 



uncurled, measured, and counted. The dissection 

 must be made with some care to avoid injuring the 

 eggs, and the following is the method I adopt 

 myself. 



Dissection of gravid female adders. — Fix the 

 adder down on a board at the head end by means of a 

 nail or drawing-pin through the snout, the adder being 

 on its back, the belly exposed to the operator. Leave 

 the body and tail free. The best instrument to use 

 is an ordinary blunt-pointed surgical bistoury, which 

 is a long thin-bladed knife with a blunt point. A 

 sharp - pointed knife is very apt to injure the ab- 

 dominal contents. Grasping the adder's tail with 

 the left hand, insert the blunt point of the knife 

 into the aperture of the cloaca (the posterior opening 

 on the belly, that is) and gently slit up the belly from 

 behind forwards, keeping the edge of the knife in a 

 line with the edge of the successive large ventral 

 scales. Continue this incision for about half - way 

 up the body, and then withdrawing the knife, turn 

 the separated surface of the belly over to the side 

 where it is still attached. The whole of the contents of 

 the lower half of the body cavity will now be exposed. 

 Gently separate the intestines with the handle of the 

 knife, and the two large strings of eggs will be seen 

 lying underneath, one row on each side of the cavity. 

 Trace these up and down to their ends, and tie a 

 ligature round the oviduct at each end, on each side 

 — four ligatures altogether. The blood-supply to the 



