OF THE CALABAR BEAN. 779 



Experiment XCIX. 



A young rabbit was killed, and its beart was exposed. During four minutes, the contrac- 

 tions were eighty per minute. A concentrated solution of extract was painted over the greater 

 portion of the heart's surface. In one minute, the contractions had entirely ceased ; but, a few 

 seconds afterwards, the left ventricle spontaneously resumed its action, and in two minutes 

 after the application, the whole heart was contracting at the rate of seventy-six per minute. 



The application was thrice repeated with similar results. Latterly, however, a longer 

 interval occurred between the suspension and recovery of the cardiac contractility. Paralysis 

 of the heart was ultimately caused by continuing these applications. 



2. After Removal from the Body. 

 When the heart is removed from the body and placed in a concentrated solu- 

 tion of extract, its contractions immediately become irregular, and then cease. 

 All the vital properties of its structures are paralysed in one or two minutes. 



3. Insertion of Physostigma into one of the Heart's Chambers. 



Experiment C. 



A young rabbit was killed by the destruction of the medulla oblongata. In four minutes 

 afterwards, while the heart was contracting at the rate of fifty per minute, two grains of extract, 

 in five minims of water, were injected by Wood's syringe into the right auricle. The action of 

 the heart instantly ceased. However, during the next ten minutes, irritation could still cause 

 single laboured contractions. 



Topical Action on the Blood- Vessels and Pigment-Cells when applied 

 to the Web of the Frog's Foot. 



Wharton Jones has examined with great care the changes in the calibre of 

 the blood-vessels that follow the application of various substances to the frog's 

 web* Solution of atropia produces a marked contraction, a result that I have 

 had occasion to confirm ; and it, in this respect, resembles ordinary stimuli, such 

 as galvanism, temporary cold and heat, and various irritants. He further estab- 

 lished, and Lister has supported and extended the statement,! that the contrac- 

 tile power of minute blood-vessels is independent of the central organs of the 

 nervous system, though it may be controlled by them. A few substances were 

 found that cause dilatation of blood-vessels, and among them solution of opium. 



This antagonism in the actions of opium and atropia, and the well-known 

 difference in their effects on the pupil, whether acting through the blood or acting 

 by topical application, seem to have an important bearing on the question of how 

 far the movements of the iris are due to calibre-changes of its blood-vessels. 

 The examination of the topical effects of physostigma — a much more powerful 



* On the State of tlie Blood- Vessels in Inflammation, &c. ; loc. cit. 



f An Inquiry regarding the parts of the Nervous System which regulate the Contraction of the 

 Arteries; Philosophical Transactions, vol. cxlviii., 1858. 



VOL. XXIV. PART III. 10 B 



