POISON OF SOME INDIAN VENOMOUS SNAKES. 91 



nerves distributed to the respiratory muscles. The complete 

 insensibility of the phrenic nerve to the strongest stimuli, while 

 the sciatics and vagus still retained a considerable amount of 

 irritability, in Experiments XLIV and LXVI, is very remark- 

 able. The want of co-ordination between the diaphragm and 

 the thoracic muscles in Experiment LX is not improbably due 

 to paralysis of the phrenic nerve, though it may be attributed 

 to some alteration in the respiratory centre. Brown-Sequard 

 states that the diaphragm contains ganglia which will keep up 

 rhythmical movements in it after the central nervous system 

 has been destroyed ; and if this statement is correct, it seems 

 probable that paralysis of the phrenic, by interrupting the 

 connection between the respiratory centres in the medulla and 

 those in the diaphragm, may allow the movements of the 

 thoracic respiratory muscles and of the diaphragm to occur one 

 after the other instead of simultaneously. 



It is diflficult to say to what extent the stoppage of respiration 

 depends on paralysis of the medulla, or of the motor nerves, in 

 each case. Probably the effect of the one preponderates in 

 some cases, and that of the other in others. 



Experiment LXII. 



November 29th, 1872. — The vagi of a cat were exposed and 

 some dilute cobra-poison injected subcutaneoiisly. Little effect 

 being produced, the dose was repeated, and then a solution of 

 alcoholic extract of the poison injected subcutaneously and into 

 the peritoneum. After the last injection the animal became 

 feebler. No vomiting. Before death slight convulsions occurred. 

 After they ceased, a cannula was put in the trachea and arti- 

 ficial respiration begun. Slight convulsions again appeared, but 

 ceased as respiration was continued. They recommenced when 

 the respiration was stopped, and disappeared when it was again 

 begun. On once more stopping respiration and allowing the 

 convulsions to cease spontaneously, recommencement of the 

 respiration caused them again to appear. 



