726 DR FRASER ON THE PHYSIOLOGICAL ACTION 



Experiment XX. 



There was injected into the subcutaneous tissue at the right flank of a rabbit, weighing 

 two pounds, half a grain of extract in fifteen minims of distilled water. The usual tremors 

 rapidly supervened, and in forty-five minutes the animal was dead. During the following 

 thirty-one minutes, galvanism of either sciatic nerve produced contractions of the limb which it 

 supplied. 



Experiment XXI. 



Half a grain of extract was placed in the mouth of a pigeon. In ten minutes, a profuse 

 flow of saliva and of tears, with occasional passage of faeces, occurred ; after which time the bird 

 lay in a helpless condition, with now and then a sudden starting movement. In twenty-four 

 minutes, its respirations had completely ceased. Until eight minutes after death, galvanism of 

 the left sciatic nerve continued to produce movements in the left leg ; but in thirteen, the 

 nerve was quite paralysed. 



Such experiments were frequently repeated ; and in no case did I find that the 

 motor nerves were paralysed before the respiratory movements had ceased, 

 although it has occurred that they have almost immediately afterwards been so. 

 I have found that the interval during which they remain active varies greatly in 

 different animals, and in the same animal according to the dose of poison 

 administered ; and I believe that in the latter case the variation is in an inverse 

 ratio. In the rabbit, motor conductivity may be retained for periods ranging 

 from a very few (two or four) to thirty-one minutes. We cannot, therefore, 

 account for either the condition of general paralysis or the cessation of the 

 respiratory movements, which two form the most prominent of the symptoms of 

 physostigma poisoning in warm-blooded animals, by an action on the motor 

 nerves. Experiments XVII., XVIII., XIX., XX. and XXI. are sufficient to 

 prove this. The evidence obtained by experiments with frogs is even more 

 unmistakable. Complete destruction of all the vital functions in this animal 

 never occurred for many hours. In animals of a higher type, the implication of 

 one system so rapidly influences the others that it is often difficult to discriminate 

 between the effects which are caused by the poison and those which are induced 

 as results of the primary action. In the frog, on the other hand, the symptoms 

 advance so slowly from one system to another that it is possible to determine 

 distinctly the sequence of the phenomena which are due to the direct influence 

 of physostigma. 



Experiment XXII. 



Five grains of extract, suspended in a few minims of distilled water, were injected under 

 the skin over the back of a frog weighing 490 grains. A small quantity escaped in the some- 

 what vigorous movements which occurred when the frog was liberated. The thoracic respiratory 

 movements ceased in ten minutes, and those of the throat in other four. Twenty-two minutes 

 after the injection, the animal lay on its abdomen in a perfectly flaccid condition ; its heart was 

 acting feebly, at the rate of seven per minute ; and pinching of the skin anywhere caused but 

 very weak reflected movements. In one hour, no evidence could be obtained by galvanism, or by 



