DR THOMAS R. FRASER ON STROPHANTHUS HISPIDUS. 455 



than upon any direct action on the respiratory movements, is made clearly apparent 

 by the results of some of the experiments on frogs. When the heart had been exposed 

 before the administration of Strophanthus, it was found that respiratory disturbances 

 and dyspnoea quickly followed the marked changes produced in the heart's action, 

 and that the respiratory movements did not entirely cease until from 14 to 32 

 min. after the ventricle had been brought to a standstill and the circulation had 

 consequently ceased (see Experiments LIX., LXVIL, LXVIIL, LXIX., and LXXIIL). 

 The changes in respiration observed in these and other experiments are, indeed, much 

 the same as those that occur when the circulation is stopped by ligaturing the heart of 

 a frog. When this is done, the respirations soon become extremely irregular, gaping 

 movements of the mouth occur, intervals of prolonged dyspnoea are exhibited, and 

 the respiratory movements of the throat do not cease until 30 or 35 min. after 

 the heart has been ligatured (see Experiment LVIL, B). 



The independence in frogs relatively to mammals of pulmonary respiration upon the 

 cardiac action, would also lead to the anticipation that if Strophanthus acts to any 

 important extent on respiration, there should be a greater difference in the minimum- 

 lethal dose for frogs as contrasted with ra,bbits than has been found. As a matter 

 of fact, this dose is almost the same per 100 grains for each animal. If, however, 

 Strophanthus added to its emphatic cardiac action a decided paralysing action on the 

 respiratory movements, the minimum-lethal dose for any given weight of animal should 

 be considerably smaller for rabbits than for frogs ; for the added respiratory action 

 would operate in producing death, much more effectively in the rabbit than it would in 

 the frog. 



For assistance received in various parts of this investigation, I have to thank my 

 present Assistants, Dr Tillie and Mr Sillar, M.B., and my former Assistant, Dr 

 Stockman. 



EXPLANATION OF PLATES. 

 Plate VIII. 



Experiment 



LXI. Tracings of detached gastrocnemius muscle of frog. Muscle only stimulated. 1, muscle in normal 

 saline ; 2 to 8, muscle in saline solution of extract of Strophanthus (1:25,000). Tracings 3 to 

 7 show irregularities caused by fibrillary twitches. Reads left to right. 



Plate IX. 



LXII. Tracings of detached gastrocnemius muscle of frog. Both nerve and muscle stimulated; nerve 

 stimulated in tracings 1 and 8; and muscle in tracings 2, 3, 9, 10, 11, 12, 13, 14, 15, and 

 16. Tracings 1 and 2, muscle in normal saline; 3 to 16, muscle in saline solution of extract 

 of Strophanthus (1:2500). Reads right to left. 



VOL. XXXVI. PART II. (NO. 16). 3 Y 



