UPON THE VASCULAR SYSTEM. 



115 



EXPERIMENT XIV.— Strong Frog. Both Vagi Divided. Larnyx Opened. Heart 



Exposed. Pericardium Intact. 1 Daniell. 







Pulse in Half a Minute. 





Time. 



Distance in Millimetres of 



Primary from Secondary 



Coil. 





State of Laryngeal 

 Muscles. 



Before Irritation of 



During Irritation of 







Vagus. 



the Vagus. 











Left vagus. 





414' 



700 



17 



17 



Rest. 



■16' 



700—650 



17 



16 



j) 



■19' 



650—600 



16 



16 



35 



•22' 



600—580 



16 



16 



Contraction. 



•25' 



580—550 



16 



16, 16 



5> 



•30' 



550—500 



16 



16, 16 



33 



•34' 



500—480 



16, 16 



16, 16 



>! 



•39' 



480—450 



16, 16 



16 



33 



•44' 



450—440 



16, 17 



17, 17 



33 



•48' 



440—420 



17, 18 



17, 16 



>3 



•52' 



420—400 



17, 17 



17, 17 



33 



•57' 



400—380 



17 



16 



33 



•59' 



380—360 



16 



16 



33 



54' 



360—340 



16 



16, 16 



S3 



•8' 



340—320 



16, 16 



16, 16 



33 



•13' 



320—300 



16 



16, 16 



I! 



•17' 



300—280 



16, 16 



16, 16 



3 3 



•21' 



280—260 



16 



16 



3; 



•26' 



260—250 



16 



16 



33 



•30' 



240 



16 



15 



33 



•32' 



220 



16 



15 



33 



•35' 



200 



16 



16 



33 



•37' 



180 



15 



16 



33 



•42' 



160 



17 



13 



33 



•44' 



140 



17 



13 



33 



•48' 



120 



18 



12 



33 



•51' 



100 



21 



Arrest. 



33 



It is unnecessary for me to give the results of other two experiments upon 

 frogs, seeing that they are precisely similar to the above. The experiments al- 

 ready detailed amply suffice to show the method of experimentation adopted in 

 the inquiry. I am at a loss to conceive a mode of research better calculated to 

 yield accurate results. The stimulation of the recurrent laryngeal fibres of the 

 vagus served as an index of the effect of the irritant upon the very nerve sup- 

 posed to contain motor fibres for the heart, and enabled me to judge whether 

 or not the vagus was being properly stimulated. Hence the fact that I never 

 observed quickening of the heart's action follow stimulation of the nerve although 

 negative in its nature, is, nevertheless, I venture to think, exceedingly reliable 

 on account of the method of procedure adopted. It may be well, however, for 

 me to repeat, that I never registered the heart's pulsations while the animal was 

 restless ; had I done so, I might have shown that accelerated cardiac action 



VOL. XXVI. PART I. 2 H 



