108 BRITISH SERPENTS. 
The main artery to the liver is seen running along one 
margin of that organ, and the vessels to the lung can 
also be traced. Respiration in adders is very slow, 
and very difficult to count, but I once satisfied myself 
that a particular adder took seven breaths in a minute. 
They can, however, do with very little air, and have 
been known to survive in a closed bottle for a 
considerable time. 
