540 SNAKES OF CEYLON. 



(2) (a) The anti-clotting ferment accounts for the 



defective clotting capabilities produced in blood, 

 and in conjunction with (3) for the haemorrhages, 

 which are so frequently seen. 



(b) " Hemolysin " in this venom is relatively potent, 

 and hence destruction of red blood cells is 

 a prominent feature. This produces some respi- 

 ratory embarrassment and contributes to the 

 depression of vitality produced by (1) (b). 



(3) " Haemorrhagin " is relatively more potent in this 

 than in any other of our Indian snake venoms. In 

 conjunction with (2) (a) it causes profuse bleedings. 



(I) Symptoms of Echis Toxaemia : The poison of the saw- 

 scaled viper has no direct effect upon the central nervous 

 system, except upon the vasomotor centre (as shown by 

 Rogers), consequently paralyses are conspicuously absent, and 

 the chief constitutional symptoms observed are indicative of 

 cardiac weakness. In addition, the constitution of the blood 

 is profoundly altered, and the blood vessels have their lining 

 membrane damaged, with the result that haemorrhages almost 

 always occur. The local symptoms resemble those of Russell's 

 viper (q.v., page 518). 



In echis toxaemia the heart labours under great difficulties. 

 Like colubrine venoms this powerfully depresses the vaso- 

 motor centre in the brain, producing a fall in blood pressure, 

 and a weakening of the heart's pulsations. Fraser and Gunn 

 have also demonstrated a direct weakening effect that this 

 venom exerts on the cardiac muscle itself. By a destruction 

 of the red blood cells an impoverished quality of the blood 

 is supplied to the heart's muscle, which suffers again on this 

 account. Further, the activity of the heart is lowered 

 proportionately to the degree to which haemorrhages occur. 

 Over and above all these influences are the emotional ones, 

 due to anxiety, fright, and pain. It is not surprising, there- 

 fore, that death is due to heart failure. Any attendant 

 tendency to asphyxia that may present itself is brought 



