REPORT ON ANIMAL PHYSIOLOGY. 139 



that if the sensibility of the Rabbit be destroyed by a blow on the 

 head, the brain and spinal cord may be entirely removed, the 

 heart still continuing to act. By other experiments he showed, 

 that (the sensibility of the animal being destroyed,) the heart may 

 be excited to act more powerfully by stimidi applied to any part 

 of the brain and cord ; that if the stimulus be very powerful, as 

 crushing the central parts of the nervous system suddenly, the 

 action of the heart is suppressed. He infers from hence that 

 the mode in which Le Gallois destroyed the cord exhausted at 

 once the excitability of the heart in those instances in which it 

 entirely ceased to act, and impaired it in others. He remarked 

 that the increased action of the heart could generally be observed 

 as long as the stimulus, whether chemical or mechanical, was 

 applied, unless it was of a nature to produce the sedative after the 

 stimulant effect; and inferred that the former is a direct opera- 

 tion of the agent, when it is observed, and not a consequence of 

 the latter. Dr. Philip therefore concludes, with Le Gallois, that 

 the functions of the cord are independent of the brain ; and that 

 the heart is acted upon by every part of the cord. But he dis- 

 proves altogether Le Gallois' opinion that the irritability of the 

 heart is a quality derived from the cord. He proves that it re- 

 ceives no power from the central parts of the nervous system ; 

 but that nervous influence, like any other stimulant, is capable 

 of exhausting its excitability ; that it is acted upon not by the 

 cord alone, but by every part of the central masses, the brain 

 and cord : obeying a much less powerful stimulus than the mus- 

 cles of voluntary motion, but that the stimulus must extend over 

 a large surface of the brain or cord to affect the heart. 



Flourens*, from his experiments on fishes, concludes that the 

 power of the heart is inherent, and is influenced only by destruc- 

 tion of that part of the nervous system whose integrity is neces- 

 sary for respiration, , the medulla oblongata. 



Dr. Marshall Hallf, making the Frog and Eel the subjects of 

 his experiments, because the transparency of parts at different 

 distances from the heart (in the former the web and lungs, 

 in the latter the caudal, dorsal, and pectoral fins,) allowed him 

 to test the varying power of the heart to circulate the blood, 

 has deduced the following conclusions : that the heart's action 

 is enfeebled from the moment it is deprived, at once, of the in- 

 fluence of the brain and cord ; that it possesses an independent 

 irritability, which however, like that of the voluntary muscles, 

 is lost after the organ has been separated from the central masses 

 of the nervous system ; that the circulation is first enfeebled, 

 then lost, in the most distant parts of the body from the heart, 

 • Mem. de I'Institut, torn. x. t Essay, 1831. 



