CHAPTER IX. 



BREATHING AND HISSING OF SNAKES. 



FOLLOWING on the subject of the last chapter comes 

 that of respiration ; and in connection with breathing 

 is the * voice/ so far as this class of animals can be said to 

 possess a voice. 



As already seen in the description of the glottis, serpents 

 do not breathe in the ordinary way, with short and regular 

 inspirations, but when they do respire, they take in a supply 

 of air to last them for some time. Their lungs, instead of 

 occupying one particular portion of the body corresponding 

 with the chest of the higher animals, are less developed. 

 One lung — or what Professor Owen calls the long pulmonary 

 bag — of snakes extends along more than half of their body ; 

 in some species nearly to the anus. Only one lung is 

 normal, the other is rudimentary. The circulation is so 

 arranged that on each contraction of the heart only a part 

 of the blood is exposed to the influence of the air and 

 becomes oxygenated, the rest returning to the parts without 

 having undergone the action of respiration at all. The 

 blood is, in consequence, poor in red corpuscles, its circula- 



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