1906.] 



Recently-Discovered African Arrow Poison. 



43 



ately fell from 84 to 50 mm. Hg. Stimulation of the sciatic nerve now 

 produced no rise of blood pressure, showing that the peripheral termina- 

 tions of the vasomotor nerves were paralysed. Poison 1/10 gramme 

 (= 0'036 gramme per kilogramme) was now injected. The blood pressure 

 went up to a maximum height of 120 mm. Hg and from this point the 

 pressure fell as in all the other animals as the heart failed. 



Experiment 17. — Rabbit, weight 2380 grammes. Both vagi divided. 

 Blood pressure 124 mm. Hg. Apocodein 1/10 gramme injected 

 (= 0'042 gramme per kilogramme). The blood pressure after a slight rise 

 rapidly fell to 84 mm. Hg. Stimulation of the sciatic nerve produced 

 a slight rise of 4 mm. Hg and therefore a second injection of the same dose 

 of apocodein was administered. After this, stimulation of the sciatic nerve 

 produced no rise in the blood pressure, which remained at 84 mm. Hg. 



Poison 1/10 gramme (= - 042 gramme per kilogramme) was now injected. 

 At the end of the injection the blood pressure commenced to rise steadily 

 to a maximum of 160 mm. Hg. From this point the pressure fell in the 

 usual way, the action of the heart being irregular. The sciatic nerve was 

 stimulated four times after the poison was injected and the slight 

 alterations occurring in the blood-pressure curve are secondary to the 

 alterations in the respirations. 



Stimulation of the Depressor Nerve. 



Experiment 18. — Eabbit, weight 2650 grammes. Left depressor nerve cut. 

 Poison 1/30 gramme was injected intravenously (= 0'012 gramme per 

 kilogramme). 



Blood pressure. — After the pressure had risen in the usual way as the 

 result of the injection, the central end of the depressor nerve was stimulated 

 three times, the last stimulation being applied five minutes after the poison 

 was injected. On each occasion the blood pressure fell to the same extent 

 as it did on stimulation of the depressor before the poison was injected. 



A second injection of poison (1/30 gramme) was administered six minutes 

 after the first. After the blood pressure had risen as the result of the 

 injection the depressor was stimulated five times. 



The last stimulation was applied six minutes after the second injection. 

 On each occasion except the first, when the stimulation was applied just 

 as the blood pressure was commencing to rise as a result of the injection 

 of the poison, the fall of pressure was practically to the same degree. 



When the last two stimuli were applied the blood pressure had 

 commenced to fall and the heart to beat irregularly. A third injection 

 of poison (1/30 gramme) was given before the blood pressure had reached 



