438 DR THOMAS R. FRASER ON STROPHANTHUS HISPIDUS. 



vessels had been reduced to one-twentieth in 8 min., and had become almost occluded in 

 about 25 min. 



A consideration of the above experiments appears to show that dilute solutions, 

 represented by from 1 : 100,000 to 1 : 20,000 either of extract of Strophanthus or 

 of strophanthin, are incapable of producing contraction of the blood-vessels. With 

 stronger solutions some evidence of contraction is obtained ; but even with so con- 

 centrated a solution as 1 : 1000 of the extract, the maximum degree of contraction was 

 moderate, and, after contact for 35 min., a fair flow still took place through the blood- 

 vessels. 



In appreciating the slightness of the effect, it is necessary to take into account the 

 circumstances that even with normal saline the flow through the blood-vessels usually 

 becomes reduced within 30 or 40 min., and that the reduction most frequently and 

 decidedly occurs when the original state of the blood-vessels is one of dilatation rather 

 than of moderate contraction. 



The best proof, however, of the feeble power of Strophanthus to contract blood- 

 vessels is obtained when a comparison is made between the results of experiments in 

 which Strophanthus and digitalin were given in combination or separately. The con- 

 trast in the former case is clearly exhibited in the curves of Experiments CXXXIV., 

 CXXXV., CXXXVIL, CXL., and CXLII. In the case of the experiments with each 

 substance in different frogs, Experiments CXLIIL, CXLIV., and CXLV. show that a 

 solution of even 1:100,000 of digitalin promptly reduced the lumen of blood-vessels, 

 and that this was done with still greater promptness and completeness by solutions of 

 1 : 50,000 and 1 : 20,000 ; whereas no effect was produced by similar solutions of Stroph- 

 anthus extract or of strophanthin. 



No exact statement of the relative energy of the two substances is possible ; but 

 from a comparison between the results of certain of the experiments — e.g., of Experi- 

 ments CXXXV. and CXLIV., by which 1 : 50,000 of digitalin is seen to have produced 

 at least as great contraction as 1 : 500 of strophanthin, and of Experiments CXXXIII. 

 and CXLIIL, by which it is seen that 1 : 100,000 of digitalin produced as much con- 

 traction as 1 : 1000 of Strophanthus extract, it seems indicated that, in respect of 

 this action, digitalin is about 100 times stronger than strophanthin or extract of 

 Strophanthus. 



As the central nervous system had been entirely or partially destroyed in the frogs 

 used in this series of experiments, any change that is produced on the blood-vessels by 

 Strophanthus acting on nervous centres outside of them, might not have been made 

 manifest by the experiments. In the next series of experiments, however, an opportunity 

 was given for the manifestation not only of the effects of direct contact with the blood- 

 vessels, but also of any effects on them that may be produced by an action on their con- 

 trolling nerve centres. 



