OF THE CALABAR BEAN. 783 



including those of the blood-vessels : while contraction of the pupil by phy- 

 sostigma will be intelligibly explained by the universal relaxation of all the 

 contractile tissues of the iris, and the consequent enlargement of its area by 

 the increased accession of blood, which the dilated vessels attract and permit. 



The topical action of physostigma on the blood-vessels has been already 

 described, and it certainly supports the view just stated. Confirmatory evidence 

 is also obtained from Adamuk's recent experiments on intra-ocular pressure,* 

 which show that this is increased by extract of Calabar bean applied to the 

 conjunctiva and diminished by atropia ; for such a difference of effect would 

 necessarily exist, did physostigma augment the blood supply of the iris and 

 atropia decrease it. 



The additional effects that follow the topical application to the human 

 eye-ball will be mentioned among the general conclusions. 



The following are the conclusions of this investigation : — 



A. ACTION THROUGH THE BLOOD. 



1. Physostigma has proved fatal to every animal hitherto examined, with the 

 exception of the Esere moth. In mammals and birds, death is most rapidly 

 caused when the poison is injected into the circulation or when it is brought into 

 contact with a wounded surface. It follows nearly as quickly, when Calabar bean 

 is introduced into a serous cavity; much more slowly when it is exhibited by 

 the mucous membrane of the digestive system. In rabbits, death has been 

 caused by its application to the Schneiderian, the auditory or the conjunctival 

 mucous membrane. The skin of frogs resists the poison for a long time ; but, 

 if it be applied for a considerable period, and with proper precautions, distinct 

 evidence of absorption may be obtained, though death has never been caused 

 by such application. 



2. The contact of the extract of Calabar bean with the gastric juice of a dog, 

 for twenty-four hours and at a temperature a little above 95° F., did not, in the 

 slightest degree, modify the energy of the poison. 



3. A large dose, given to a mammal or bird, rapidly affects the cardiac con- 

 tractions, and then paralyses the heart. The respiratory movements are quickly 

 stopped, but the symptoms and post mortem appearances are those of syncope. 

 Such a dose, injected into the abdominal cavity of a frog, affects nearly simul- 

 taneously the heart and spinal cord, and very rapidly destroys the vitality of 

 both organs. In this case the motor nerves are only slightly, or not at all 

 affected, and may retain their conductivity for about thirty hours. Evidence of 



* Centralblatt, No. 36, 1866 ; and Rutherford's Report on Physiology, Journal of 

 Anatomy and Physiology, No. II., 1867. 



VOL. XXIV. PART III. 10 C 



