OF THE CALABAR BEAN. 773 



In many other experiments, the pupils are described as having contracted 

 during the poisoning, but the exact changes were not measured. In the Table, 

 Experiments LXXV., LXXVIII,, LXXXIIL, LXXXVH., LXXXVIII. and 

 LXXXIX. illustrate the rapid change that frequently occurs from contraction 

 to dilatation ; and it is obvious that unless special and continued attention be 

 directed to the condition of the pupils, the contracted state will frequently escape 

 detection. Harley,* Amedee V~EE,t Nunneley,J Laschkewich§ and Van 

 Hasselt II agree with me in describing contraction of the pupils as one of the 

 effects that follow the internal administration of Calabar bean. 



It is, unfortunately, impossible to enter fully into the question of the method 

 in which physostigma produces its effects on the pupil, as the physiology of pupil- 

 lary changes is yet unsettled, and as even the structural anatomy of the iris is a 

 subject of debate. I am anxious to avoid being committed to any theoretical 

 assertion on this subject, especially as the opinions I previously expressed do not 

 seem so certainly supported by my further experience as to permit of their 

 reassertion . 



Many endeavours have been made to arrive at some definite conclusion, and, 

 although this has not yet been attained, as in the state of our knowledge of the 

 anatomy and normal physiology of the iris it could not be, the probable method 

 of action may be indicated with the aid of the following experiment. 



Experiment XCIII. 

 The two sympathetic nerves were exposed at the neck of a white rabbit. Both pupils had 

 a diameter of seven- fiftieths of an inch. The left sympathetic was divided. 

 In 2 minutes, left pupil = 5, right == 7. 



I then endeavoured to fix definitely the strength of the weakest interrupted galvanic current 

 that could so stimulate the portion of the divided sympathetic next to the eye as to produce 

 dilatation of the pupil. For this purpose, Daniell's cell and Du Bois Keymond's induction 

 apparatus were employed. 



When the secondary coil was at 500, the resulting current produced no effect on the pupil in 30 sec. 



480, 

 400, 

 300, 

 250, 

 200, 



„ 150, the left pupil dilated from 5 to 15, immediately. 



„ 190, the resulting current produced no effect on the pupil in 30 sec. 



„ 185, the left pupil dilated from 6 to 15 in 10 seconds. 



One grain of extract, in fifteen minims of distilled water, was injected into the subcutaneous 

 tissue of the right flank. In thirty seconds, tremors occurred ; and the symptoms rapidly advanced 

 to a fatal termination, fifteen minutes and thirty seconds after the administration of the poison. 



* Op. cit. p. 140. "f" B,echerches sur la Feve du Calabar, 1865, p. 22, &c. 



+ Op. cit. p. 12. § Op. cit. p. 300. 



|| Mentioned by Donders (Accommodation and Kefraction of the Eye : New Sydenham Society, 

 1864) as having been observed in 1856 ; and, I am informed by Professor Donders, communicated 

 to a scientific society, but not otherwise published by Van Hasselt. 



