THE ACTION OF VENOMS UPON THE PULSE-RATE. 69 



Summary and Conclusions of the Actions of Venoms on the Pulse-rate, The 

 results of this series of experiments indicate that the primary tendency of venoms 

 is to cause an increase of the pulse-rate, that this tendency is greater after section 

 of the pneumogastric nerves, and that it rarely occurs after conjoined section of 

 the pneumogastric nerves and the -upper or middle cervical region of the spinal 

 cord. 



From the increased tendency to acceleration of the pulse-rate in poisoning by 

 venom after section of the pneumogastric nerves we infer that there is some direct 

 or indirect effect of the venom upon the pneumogastric centres by which an inhibi- 

 tory influence is exerted, and which tends to neutralize the action bringing about 

 acceleration. Since hastening of the pulse is a rare occurrence after conjoint 

 section of the pneumogastric nerves and the cervical spinal cord, we think that 

 the increase is due for the most part to some effect upon the accelerator centres 

 in the medulla, whereby impulses are sent through (chiefly at least) those of the 

 accelerator fibres which pass by the cord. The increase of the pulse-rate which 

 may occur after division of the nerves distributed to the heart, by section of the 

 pneumogastric nerves and cervical spinal cord, must be dependent upon a direct 

 action of the venom upon the heart muscle or its contained ganglia. 



The diminution in the heart beats must be due to a direct cardiac action, since 

 it occurs after isolation of the heart, as above, from any central nervous influence. 



In these as in all other experiments which involve intravenous use of venoms we 

 are liable to disturbing elements which do not trouble our explanations in dealing 

 with other poisons. At any moment, anywhere in nerve-tissue or muscles, we may 

 have abrupt and quite countless hemorrhages. How these may introduce con- 

 flicting symptoms and modify results has already been pointed out by one of us 

 many years ago. 1 They make absolute constancy of effects quite improbable. 



SECTION II. THE ACTIONS OF GLOBULINS ON THE PULSE-RATE. 



The Actions of the Venom Globulins on the Pulse-rate. The actions of the venom 

 globulins upon the pulse-rate appear to differ somewhat in quality from what is 

 found in poisoning with pure venoms; there is a greater tendency to the primary 

 increase in the pulse than with pure venoms, while the action by which this is 

 brought about seems to differ. 



Of eleven experiments in which the amounts used represented the proportion 

 of the respective globulins contained in the usual doses of venom given, six were 

 made with the water-venom-globulin, two with the copper-venom-globulin, and three 

 with the dialysis-venom-globulin ; all of these poisons, excepting in one experiment 

 with the water-venom-globulin of the Ancistrodon, were derived from the venom 

 of the Crotalus adamanteus. 



The water-venom-globulin seems to be the most active, and the copper-venom- 



1 Researches on the Veuom of the Rattlesnake. S. Weir Mitchell, 1861. 



