1874.] Poison of Indian Venomous Snakes. 123 



that the central nervous system is little concerned in the arrest of circu- 

 lation by the poison, at least in the frog. 



The stoppage of the excised heart may be due (1) to irritation of the 

 inhibitory centres contained within it, or (2) to paralysis of its motor 

 ganglia, or (3) to excessive stimulation of them producing tetanus, or 

 (4) to the action of the poison on the muscuk. fibre of the organ. It is not 

 due to the first of these causes ; for atropia,which paralyzes the inhibitory 

 ganglia, does not restore the movements. The second is improbable, as 

 the heart does not stop in diastole but in systole, and resists distention 

 by fluid within it. The third seems the most probable cause, as one does 

 not see why the poison should arrest the cardiac pulsations at once when 

 applied to the interior of the organ, and not do so when placed on the 

 outside, if it acted on the muscular fibre, whereas it may readily be sup- 

 posed that the poison may reach the ganglia more readily from the inner 

 side of the heart though we do not venture to assert that this is the true 

 explanation 'of the facts we have observed. 



The inhibitory branches of the vagus are not always paralyzed (Expe- 

 riment LXVI. ; but sometimes the cobra-poison appears to affect them as 

 well as the motor nerves ; and in this it resembles curare, which in small 

 doses does not impair the inhibitory action of the vagus, but in large 

 doses completely destroys it. In Experiment LVI. irritation of the vagus 

 quickened, instead of retarding, the cardiac pulsations a circumstance 

 which indicates that the inhibitory fibres of the vagus were paralyzed by 

 the poison, but not the accelerating ones. 



The capillary circulation is not unaffected by the poison. In Experi- 

 ment IV. of our former paper, the rhythmical contractions and dilatations, 

 altogether independent of the cardiac pulsations, which Schiff first observed 

 in the rabbit's ear, and which were noticed by Ludwig and Brunton in 

 the vessels of many parts of the body, were greatly increased by the 

 injection of the poison. 



In Experiments LXXIV. and LXXV. the blood-pressure remained 

 high after the heart had ceased to beat. This shows that the arterioles, 

 or capillaries, must have been much contracted, thus opposing a barrier 

 to the exit of blood from the arteries into the veins. 



Experiment LXVII. 



May 2~Lst. A cannula was placed in the trachea of a large black rabbit ; 

 and some dried cobra-poison dissolved in water was injected into the hip 

 at 1.25 P.M. 



1.50. The animal shows symptoms of poisoning. Limbs becoming 

 weak. There is trembling, and the body sinks down. There is starting. 

 The respiration is hurried. 



2. Reflex action is well marked when the animal is touched. The limbs 

 seem almost paralyzed ; but the animal moves the head and neck freely. It 

 makes efforts to ris?, but is unable to do so. The head falls over ; the 



