STROPHANTHUS SARMENTOSUS : ITS PHARMACOLOGICAL ACTION. 409 



sations are usually limited to small portions of its wall. Paralysis of the vagus 

 by atropine, after the cardiac effects have been developed, does not modify these 

 effects, nor does paralysis of the vagus, before and during the administration of 

 the extract, prevent the occurrence of the changes in the heart which are 

 characteristic of the action of Strophanthus. 



The cardio-inhibitory function of the vagus nerve is not increased or otherwise 

 appreciably modified by S. sarmentosus. 



On the blood-vessels, the action of the extract is slight, for very strong 

 solutions cause only an unimportant degree of contraction. 



& sarmentosus does not appear to affect the blood-pressure excepting through 

 the changes produced in the heart's contractions. No evidence was obtained of 

 a hsemolytic or a blood-clotting effect, in vivo. 



The lymph- hearts of the frog are practically unaffected by this substance. 

 F. The chief effects on respiration are attributable to the action on the heart, though 

 there may also be a direct action on respiration through its medullary centre. 

 The nature of this effect is first increase and then decrease of the respiratory 

 movements and rate. 



It would appear, accordingly, that the action of S. sarmentosus is very 

 similar to that of S. hispidus. 



EXPLANATION OF PLATES. 



Plate I. 



Fig. 1. 5. sarmentosus plant, climbing up a forest tree in the Gambia Colony. Illustrating its vine-like 

 habit, and showing many double-follicle fruits and leaves, and, indistinctly, a few flowers. 

 The flowers appear in April, at which time the follicles of the previous year are approaching 

 maturity. From a photograph taken by the late Dr J. Everett Dutton in April 1903. 



Fig. 2. A flowering twig of S. sarmentosus. The long tail-like prolongations of the corolla are yet bent 

 back and spirally twisted together, and do not, therefore, display the full length of these pro- 

 longations. Drawn in the Gambia Colony by the late Dr J. Everett Dutton in April 1903. 



Fig. 3. Seeds of S. sarmentosus. a, ventral, and b, dorsal surface. 



Figs. 4a and 46. Northern Nigerian poisoned arrow-heads, presented by Sir Frederick Lugard, 

 K.C.M.G., when High Commissioner of Northern Nigeria. Actual size. The dark brown colour 

 represents the poison. 4a, usual form of arrow-head ; 46, less usual form, with lateral spikes. 



Plate II. 

 Experiment. 



L. Tracings of detached gastrocnemius muscles of frog. Read from left to right. 1, muscles in Ringer's 

 solution only. 2, muscle B in a solution of extract of S. sarmentosus in Ringer (1 in 1000) shows 

 no change. 3 and 4, muscle B has shortened, but after contraction it relaxes considerably. 

 5 and 6, stage of shortening is over and muscle B contracts less than muscle A ; the relaxation of 

 muscle B is slightly delayed. 7, contraction and relaxation of muscle B are more gradual than 

 those of A. 



TRANS. ROY. SOU. EDIN., VOL. XLVII. PART II. (NO. 15). 61 



